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How to Kill Whiteflies

The name “whitefly” is a bit of a misnomer. Yes, this insect is white but there is no “fly” in the family tree. Genetically, whiteflies are much closer to sap-sucking aphids and they bear a striking resemblance to very small moths. If you have a large infestation and you disturb the whiteflies, they’ll fly away and create a miniature snow storm of white flecks.

Whiteflies are also a bit sneaky. Adult whiteflies lay eggs on the underside of leaves. It could be argued that whiteflies “hide” their eggs there, and in many instances, the eggs do escape detection. The adult whitefly female can lay hundreds of eggs on the underside of leaves, usually in a circular pattern. In hotter weather, one whitefly can even go from egg stage to grown adult in just 16 days. Since whiteflies live for a month or two, in warmer climates and in greenhouses, the reproduction cycle is almost continuous and the growth of the population is geometric.

You’re likely to find whiteflies in warmer regions, including greenhouses. Then again, whiteflies are survivors, and they won’t turn away from cooler temperatures. They can attack fruits, vegetables and ornamental plants with equal enthusiasm. No matter where you live, it’s important to know how to kill whiteflies and protect your plants.

How to Protect Your Plants from Getting Infested with Whiteflies

Whiteflies take their nourishment from the host plant by sucking on plant juices. When a plant has multiple whiteflies attached, the plant becomes weak and is more prone to viral diseases that whiteflies carry. Whiteflies then turn the juices into a thick, gooey substance called honeydew. The honeydew attracts sooty mold and a blackish fungus — in some cases, the honeydew covers so much of the plant that they are not able to photosynthesize properly. If you find leaves that are damaged from whiteflies, cut them off immediately.

If you’re looking for other ways to control whiteflies, chemical pesticides are not always the best solution. There are two main drawbacks to this approach: 1) Whiteflies often develop a tolerance to the toxins, much like viruses mutate to make certain antibiotics ineffective. 2) Pesticides are indiscriminate killers. You want to kill whiteflies, but you want whitefly-destroying bugs to live.

Your best bet for stopping a whitefly infestation is to be vigilant before an infestation occurs. Do a thorough and careful inspection of all your plants twice a week — inspect them more frequently if you have experienced an outbreak. Remember that the pre-adult whiteflies are almost clear, so they appear to be the same color as the leaves. Be sure to check the undersides of leaves as well, since most whiteflies are drawn to this area.

8 Safe and Natural Ways for Getting Rid of Whiteflies

So what are the options for ridding your garden or home of a whitefly infestation? Here are some methods for killing whiteflies in the most effective, environmentally sensitive way. These can be done alone, but they can also be combined for greater impact:

1. Controls — Insecticidal soaps & neem oils are best if you have children & pets in the house. Both leave a small environmental footprint. Neem oils work by suffocating the insect, but you should follow the instructions exactly to prevent burning or scalding plants. Test plants by administering neem oil to a small section and waiting 24 hours to see if burning/scalding occurs. Soaps and oils kill on contact, so don’t forget to reapply two or three times. These solutions work best if the temperature is less than 90 degrees. Hotter temperatures also encourage browning or wilting leaves.

2. Aluminum Reflective Mulch — The mulch makes it difficult for whiteflies to find the host plants. They are, in a sense, blinded by the light. This approach is particularly good for protecting your vegetables from diseases that whiteflies can transmit.

3. Yellow Sticky Traps — Use these to collect whiteflies lurking among your crops. Not only will they capture annoying little whiteflies in your home or garden but will also get rid of aphids, thrips, leap miners, gnats and fruit flies. These flies are drawn to yellow and our Safer® Brand Sticky Whitefly Trap is sticky enough to catch the pests.

4. Water — Use a jet of water to blast whiteflies and wash them off your plants and leaves. You should then rub a weak solution of insecticidal soap onto the leaves in the late afternoon. Repeat this process every week to control and get rid of whiteflies.

5. Vacuum — This is one of the best ways to get rid of whiteflies on plants if the infestation is limited to a few plants or a small area.

6. Natural Predators — You can purchase spiders, female beetles, parasitic wasps and lacewings at most gardening shops and add them to your garden to battle whiteflies without hurting beneficial plants. While female beetles and lacewings eat the eggs of whiteflies, spiders “net” the grown whiteflies for food and parasitic wasps lay eggs inside the whitefly’s body. The larvae use the host insect as food before moving on to the adult phase.

However, ants are insects you don’t want if you have whiteflies. Ants eat the honeydew and they are focused on protecting this food source. If you’re introducing beneficial bugs to your garden, put ant traps at the stems of plants with whiteflies. You should also put traps under plants that are growing close to the infected ones.

7. Environmental Controls — Pruning the affected vegetation may be helpful in reducing whiteflies. Again, put ant baits on the ground to control ants.

8. Nitrogen Levels — Check the soil content of your garden or around trees to make sure you don’t have too much nitrogen in the soil. With good intentions, people may use fertilizer that has been highly enriched with nitrogen, only to be inadvertently creating an environment that’s conducive to whiteflies.

You can also consider growing your young plants indoors until they are big enough to survive an attack. This is usually in late winter to early spring, depending on your location. If you can’t keep your young plants inside, cover them with something that lets the sun in but keeps the whiteflies out.

Symptoms of Whitefly Damage

Whiteflies, in both the nymph and adult stages, feed on plants by sucking juices from the plant tissue. As a result, an infected plant may not appear to be fully developed.

Another symptom is honeydew, a sticky material, that is secreted on the plant leaves by the whiteflies.

Results of Whitefly Infestation

Plants may become weakened from the feeding of whiteflies. They may become so weakened that they may become more susceptible to disease or they may even die.

The honeydew whiteflies secrete can attract black fungus and sooty mold.

Viral diseases can be transported by whiteflies, resulting in severe damage or death to the plant.

Controls

What?

The use of insecticidal soaps and neem oil are two excellent methods of dealing with soft-bodied, garden insects such as whiteflies.

How?

Neem oil products work by suffocating the insect. Use all neem oil products by following the instructions since, as an oil, there is greater risk of phototoxicity (burning). Avoid using sulfur based fungicides within the active period (5-7 days) of the neem oil product. These two products combined greatly increase the risk of plant burn.

Safer® Brand offers a variety of whitefly control products to help control and eliminate this garden pest and revive your plants. Please check out our whitefly control products for more details about how they work and how, when, where they should be applied.

Carefully read and follow all instructions on the product packaging for best results. It is recommended with any pesticide to test plants for sensitivity to the product. Spray a small section of the plant in an inconspicuous area and wait 24 hours before applying full coverage.

When?

Since these formulas are contact killers and they do not persist in the environment, several applications may be needed for control. As a general rule, much like watering, do not use these products in the peak of the day or when temperatures exceed 90 degrees F to avoid wilting or browning of the leaves.

Why Choose a Natural Solution?

Insecticidal soaps and neem oils can be used around children and pets. They break down into their natural elements within 7 to 10 days leaving no residual impact on the environment.

They are highly preferable to synthetic pesticides with toxins that can kill beneficial insects and cause long-term detrimental effects on the environment. Another negative effect of the chemical pesticides is the whiteflies’ possible buildup of resistance to the chemicals in the pesticides.

Whitefly

There are 2 main species present in New Zealand, Greenhouse Whitefly (Trialeurodes vaporariorum) and Citrus Whitefly (Orchamoplatus citri).

Whiteflies are small white sap sucking insects 1-2mm in length that resemble miniature moths with a wingspan of around 3mm. Both the nymphs and the adult insects are sapsuckers. Their feeding can harm the vigour of the plant, and help spread disease. As they feed they excrete a sugary substance (honeydew) and if left can allow sooty mould to grow on the leaves.

During warmer periods they can breed prolifically. The female whiteflies lay their eggs on the underside of a plants upper leaves. After 4-12 days the eggs hatch into crawling, sap-sicking nymphs.

Prevention

Nicotiana (an attractive flower) is believed to attract whitefly and can be grown as a sacrificial plant or to serve as an early warning of their presence.

Various beneficial predatory insects will prey on whitefly and can help control numbers. To help attract beneficial predator insects grow a wide array of flowering plants including: alyssum, borage, hyssop, lavender, will help attract them. For more ideas

Treatment

Spray with Mavrik. Repeat spraying twice in one week. Follow up spraying may be required in some circumstances.

Where possible, spray in the evening to avoid affecting beneficial insects.

Natural Option

Spray affected plants with Bugtrol, a highly effective organic insecticide. Spray the plant thoroughly, drenching the tops and bottoms all the leaves, twice in one week. If you spray this effectively dealing with whitefly should be easier as the eggs are smothered by the oil contained in this spray.

Follow up spraying may be required in some circumstances.

Where possible, spray in the evening to avoid affecting beneficial insects.

Net produce

Citrus whitefly

While greenhouse whitefly seems to have been here almost forever, a much more recent introduction is now causing concern. The Australian citrus whitefly, Orchamoplatus citri, was first reported in 1990 in Auckland and is now widespread throughout the North Island in all the main regions where citrus is grown.

In appearance, there’s not a lot of difference between these two whiteflies but they are different species and stick to different host plants. If you have whiteflies on your lemon tree and whiteflies on your tomatoes, you will have two different species of whiteflies each keeping pretty much to their own range of host plants.

Both these whiteflies lay tiny eggs on the undersides of the leaves which hatch into larvae, known as crawlers, that don’t actually move very far they just sit there sucking sap from the leaves and out their rear ends exude honeydew which drops on to leaves and fruit below. The sweet, sugary honeydew soon becomes infected with sooty mould fungus, giving leaves and fruit a dirty, black appearance. Larvae moult several times, eventually pupate, then emerge as adult whitefly, and so the cycle continues.

Controlling greenhouse whiteflies can be problematic as they’ve developed resistance to many widely-used insecticides, and most gardeners prefer not to spray food plants intended for the table anyway. Commercial tomato growers control them with a tiny parasitic (non-stinging) wasp (Encarsia formosa)which lays its eggs in the whitefly nymphs. The wasp larva develops inside the nymph, eventually killing it. The larva pupates and emerges as an adult wasp ready to mate and lay eggs in more whitefly nymphs. In the home garden there are several ways to keep greenhouse whitefly populations down, though you’ll probably never get rid of them completely. I used to have major problems in my vegetable garden every summer but now, by growing plenty of nasturtiums among the tomatoes and courgettes, greenhouse whitefly are almost non-existent and some of the natural predators can do their thing without being hammered by insecticides. There’s also the added bonus of juicy nasturtium flowers and leaves for the salad. Alternatively, as soon as you spot whiteflies, apply a spray such as pyrethrum, neem or Yates Mavrik, making sure you get good coverage under the leaves. It’s a good idea to spray early in the morning or in the evening as adult whiteflies are less active in cooler temperatures. You may have to spray every seven to 10 days over the heat of summer to control them.

Botanical & Biological Controls For Whiteflies

Whiteflies (“whitefly” or “white fly”) are common pests of indoor crops, greenhouses and tomatoes. Seasonal pests in most outdoor areas, whiteflies can be found year-round in southern states or enclosed growing areas (greenhouses, hoop houses, grow tents). Their rapid reproduction rate makes them difficult to control once established. Many varieties have also developed chemical resistances, making certain chemical controls ineffective. In addition to the physical damage they cause, whitefly infestations and the honeydew they produce can harbor sooty molds that reduce plant vigor causing unnecessary stress to the plant and the grower.

Identification & Prevention:

Growers often spot them by the plume of whiteflies that take flight after disturbing an infested plant. By this point, control is difficult to achieve. Early identification can be done by placing yellow stick traps around the growing area (pay attention to susceptible crops) and monitoring the undersides of leaves. Whiteflies tend to cluster and are much easier to spot in groups. Another indicator that whiteflies are around is honeydew on the leaves. It appears shiny and is sticky to the touch. Remove honeydew by wiping leaves with Green Cleaner or a diluted alcohol solution.

How To Control A Whitefly Problem:

  1. Carefully inspect new plants before transplanting. Dip foliage and root ball in soapy water to clean and kill any existing whitefly eggs, nymphs or adults.
  2. Release Green Lacewing early in the season so larvae can feed on whitefly eggs or nymphs before the infestation becomes severe.
  3. For high whitefly populations, release specialized predators & parasites for best control. E. formosa and E. eremicus are species-specific parasites effective in many environments. A. swirskii are predatory mites effective in warm, humid areas.
  4. Beauveria bassiana sprays (BotaniGard, BioCeres) are effective for ongoing control of whiteflies in gardens or commercial growing. They use the fungus to slow feeding/reproduction and kill the infected pests. Using biorational control sprays also helps limit environmental impacts on non-target organisms like bees and pollinators.
  5. If necessary, knockdown sprays of contact insecticides will quickly reduce whitefly numbers. Repeat applications may be necessary as most sprays have little residual impact.
    • Neem is a growth and feeding inhibitor commonly used by organic gardeners for general pest control.
    • Pyrethrin sprays are excellent for rapid reduction of large pest populations, but should not be applied to flowering plants.
    • Horticultural Oils are an effective knockdown for use in-season and for controlling overwintering or dormant life stages.
  6. Make sure to clean everything in the greenhouse with OxiDate or SaniDate between growing seasons. Soil drenches may be needed to control overwintering pests and/or diseases.

Learn more about controlling whiteflies or browse control options below.

There are a number of bugs that can infest your plants, either indoors or outdoors. If you notice your plant is not growing the same as it once did, is a different color, or has visible bugs on it, you need to take action in order to save your potted plant.

Plants are known to bring around bugs, after all many bugs sustain life by using plants as their food and home. Carefully inspecting your plants on a regular basis will help prevent an outbreak from getting too bad. Here we detail the most common types of bugs found on plants, as well as ways you can help prevent an infestation from taking your favorite potted plants hostage.

6 Of The Most Common House Plant Bugs:

If you are dealing with a bug infestation on your potted plants, you might be unsure what sort of bug you are dealing with. This list of the most common plant pests will help you determine the type of critter ‘bugging’ your plants.

1. Aphids

Aphids are commonly found on houseplants, and can deter plant growth by removing sap from the plant. Eventually, this robs the plant of vital nutrients, while the aphids colony continues to grow. Plants that have a serious aphids infestation become sticky with the honeydew this bug secretes.

This bug is usually visible on the underside of leaves huddled together in a cluster, and can be the same green color as your plant. The most natural way to get rid of aphids is to introduce ladybugs into the picture. (Read more about Aphids)

2. Spider Mites

You may need to bust out the magnifying glass in order to spot signs of spider mites, as these bugs are incredibly tiny. Plants that have spider mites typically lose their bright green coloring in exchange for a dull brown or washed out appearance.

Severe infestations will come with webbing all over the undersides of the leaves, and at this point it becomes difficult to eradicate the mites. Insecticides will not work to get rid of spider mites because they are not insects.

Steps to take to solve a spider mite infestation:

  • Isolate your plant
  • Use soap and water to spray the plant on a regular basis, remember spider mites reproduce at a rapid rate every 3-7 days.
  • If possible, relocate the infested plant to a humid space, spider mites like dry air for breeding.

(Learn more about Spider Mites)

3. Mealybugs

We have discussed mealybugs in a previous blog; these very determined bugs tend to return time and time again. A white cotton-like ‘fluff’ growing over your plant can identify mealybugs. The white is partially the mealy bugs but also it is the waxy substance the bug secretes, which also works to help protect them from being sprayed off.

A Q-Tip with alcohol on it can be spread over the plant to kill off the mealybugs. You want to continually dose the plant with a stream of water to loosen all of the mealybugs. Next, apply a generous coat of neem oil over the plant so that the bugs are unable to return. (Read more about Mealy Bugs)

4. Whitefly

The whitefly is able to leave the plant the moment you start spraying it, but as soon as you stop spraying the whitefly will return, this is why attacking mature whiteflies is useless. Instead it’s the baby whiteflies you want to go after because they do not move. Dipping leaves in insecticidal soap or spraying the plant regularly can help get rid of the larva so that you don’t continue to have an issue with whiteflies. (More on Whiteflies)

5. Scale Insects

Scale insects are hard to notice at first and often grow into quite a colony before being detected. At only 3mm in length on average, scale insects have a brown shell that offers them protection against things like pesticides. Scale insects derive life from sucking the juices from your plant, as a colony grows they will start to cause obvious damage to your plant. You can kill them by using a cotton swab or Q-tip soaked with alcohol. (More information on Scale insects)

6. Thrips

These small, dark bugs are hard to see, plus they have wings and so when you spray the plant, you may notice they take off for flight and move to an adjacent plant. For this reason, a plant infested with thrips should be isolated. Thrips burrow into the leaves suck up the plant juices and leave behind noticeable scarring in the leaves. (Learn more about Thrips here)

Preventing Bugs From Infesting Your Plants

Sometimes, no matter how hard you try a bug will find its way into your plant and create an entire colony. But for the most part, with careful watch and precautious plant care you can help keep the bugs from populating your greenery.

Ways to help keep bugs from infesting your plants include:

  • Keep new plants isolated for at least one month before exposing the other plants to a possible bug. Check your isolated plant frequently for any signs of distress or infestation.
  • Thoroughly clean the planter whenever repotting a plant
  • Always keep your planters clear of old, dead leaves and foliage
  • Use sterile potting soil. If you use garden soil for your planters you can encounter a world of issues, only partially related to bugs.
  • Give your plants a good cleaning here and there using a soft cloth and lukewarm, non-toxic soap.
  • Inspect plants regularly; a magnifying glass can be helpful to identify the start of mites, or other bugs, before they balloon out of control.

Should You Use Pesticides And Insecticidal Soaps On Your Plants?

Some pesticides might advertise for use on plants, but many are too strong and high in toxicity, causing damage to a plant faster than a bug colony. Also, most pesticides are not for use on indoor plants and require a well-ventilated area. Pesticides come with side effects to the environment, as well as your health. If at all possible, it’s best to find alternative, more natural solutions to getting rid of pests on your plants. If you must use a pesticide, you should always read the directions carefully and only use as directed.

Insecticidal soap is made of a potassium fatty acid that works against 40-50% of infestations related to soft-bodied bugs. Larger bugs or bugs with hard shells are much more difficult to get rid of using an insecticidal soap. Although more gentle than some pesticides, insecticides are still toxic and can cause irritation to human skin, as well as damage to your plants. Try spot treating first to make sure there are no negative implications to your plant before applying any substance over the entire surface (Read Here).

Much like aphids, whiteflies are a scourge in the garden. These tiny pale pests suck the sap from plants and spread diseases. Worse yet, they’re so miniscule that they can fit through a lot of mesh screening. Because of this, the whitefly is also a major problem in greenhouses and indoor growing spaces.

But don’t panic, you can eliminate these white insects from your greenhouse or garden. Let’s talk about whiteflies, how they multiply, and how to get rid of them!

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Organic Products to Kill Whiteflies

  • Safer Soap
  • Bonide All-Seasons Horticultural and Dormant Spray Oil
  • Safer Brand Yard & Garden Spray
  • Take-Down Garden Spray

Environmental Products to Eliminate Whiteflies

  • Yellow Sticky Traps
  • Ladybugs
  • Lacewings

Prevention Options for Whiteflies

  • Neem Oil
  • Tanglefoot Tangle-Trap

Whiteflies Overview

Common Name(s) Whiteflies, citrus whitefly, ash whitefly, greenhouse whitefly, and many other related names
Scientific Name(s) Multiple, all in the Aleyrodidae family of insects
Family Aleyrodidae
Origin Worldwide
Plants Affected Most agricultural crops (especially brassicas, tomatoes, capsicum and citrus), some ornamentals, some medicinal crops
Common Remedies Removal of pests (with water or vacuum), garlic sprays, insecticidal soaps, horticultural oils, pyrethrin-based sprays, yellow sticky traps, whitefly predators (such as ladybugs, lacewings, whitefly parasite, hummingbirds, and dragonflies), neem oil, reflective mulches, and sticky ant traps around fruit trees

Life Cycle Of Whiteflies

Rings of whitefly eggs on a leaf. Source: Scot Nelson

In the latter part of spring, whitefly adults place their eggs on the undersides of leaves. Typically, these are done in concentric patterns, towards the upper portion of the plant. An adult whitefly can produce 200-400 eggs.

Five to ten days later, the whitefly eggs will hatch into nymphs. The first instar, or larval phase, the nymphs are referred to as crawlers. They move a short distance away from their egg and then flatten against the leaf to feed. There are a total of four instars, but once the crawler has picked its location, it remains there throughout further instars.

These nymphal stages can be hard to identify. Once they’ve stopped crawling and latched onto the leaf, they look very similar to scale insects. Often their coloration blends in with the leaf they’re on, or is slightly paler in hue.

After the nymphal stages have concluded, the whitefly larva will pupate. Within a week, the whitefly emerges from its old skin as a new adult to begin its own egg-laying process. These tiny white flying bugs can live for a couple months as adults before dying off.

Common Habitats For Whiteflies

Some whiteflies on a leaf. Source: Fluffymuppet

Whiteflies live the majority of their lives on or near their host plants. While adults can fly and thus can find new plants to lay eggs on, the nymphs don’t leave their food source.

Nymphs overwinter on their host plants on the underside of leaves, where they’ve latched on to feed. However, they don’t tolerate extremely cold climates well and will die off if they are exposed to freezing conditions.

This makes them a common greenhouse pest, as the climate inside a greenhouse is usually warm enough for them to survive. In fact, there is a particular species of whitefly, the greenhouse whitefly (Trialeurodes vaporariorum) which tends to live most of its lifespan indoors!

Adult whiteflies cannot survive for more than a few days without feeding on plant sap. If you’ve found tiny white bugs on plants, you may have found whiteflies. They may be eating, laying eggs, or sheltering from inclement weather.

What Do Whiteflies Eat?

Citrus whiteflies. Source: Scot Nelson

Both adults and nymphs feed on plant sap. However, different species of whiteflies feed on different kinds of plants. For instance, the cabbage whitefly (Aleyrodes proletella) feeds on brassica species.

There are whiteflies that feed on a wide range of different agricultural crops, including citrus, most vegetables and fruits, and some ornamental plants. Worse yet, whiteflies are a vector for nearly a hundred different plant diseases, and can spread those diseases during feeding.

They also leave behind honeydew, a sticky substance that can develop black mold or other fungal issues.

How To Get Rid Of Whiteflies

A bad whitefly infestation. Source: DocJ96

So now you’re asking how to get rid of whiteflies, I’m sure. While these pests can be tricky to eliminate, especially if they take up residence inside your greenhouse, there are ways to combat them. Let’s go over some of the best white fly treatments and find the right option for you!

Organic Whitefly Control

Before trying more serious white fly treatments, you should begin with something very simple: blast your plants with water. Sometimes, a good hard spray with a hose will knock off the whitefly nymphs. As they don’t move after the creeping phase, they will starve and die. This also works surprisingly well for aphid infestations.

Use a handheld vacuum to suck white flies up! While you have to exercise caution while doing this, a small handheld vacuum can be a very easy way to get rid of larvae, eggs, and the tiny white bugs themselves. Just be careful not to let it suck the leaves off your plants.

A good home remedy for whiteflies on plants is a homemade garlic spray. Garlic can be a particularly pungent aroma, so I don’t recommend this for use inside the house! Even in a greenhouse, the scent builds up. I recommend this only for outdoor use.

An insecticidal soap like Safer Soap can be used to knock down heavy infestations. Insecticidal soaps coat the eggs and larvae with a coating that makes it difficult for them to breathe. It’ll also kill off adult whiteflies.

Horticultural oils are also quite useful on this type of pest. I recommend neem oil or something like Bonide All-Seasons Horticultural and Dormant Spray Oil. Both will smother all life stages of this pest and cause them to die off.

If none of the above work, opt for a pyrethrin-based spray. My preferences are Safer Brand Yard & Garden Spray or Take-Down Garden Spray, both of which contain pyrethrin plus an oily or fatty agent. The fats or oils coat eggs and nymphs and smother them while the pyrethrin poisons all life stages. These are both easy on the plants, too!

Environmental Whitefly Control

Whitefly, sp. Aleyrodidae. Source: gailhampshire

If you have tiny white flying bugs in house or greenhouse, or even outdoors in the garden, you can use traps to catch them. My preferred choice is yellow sticky traps. White flies are drawn to the yellow color, assuming it’s a flower. They can’t escape to go and lay eggs.

Natural predators for this white bug include ladybugs, lacewings, and the whitefly parasite (which is a form of beneficial parasitic wasp). By ensuring that you have lots of beneficial insects in your yard and garden, you can quickly deal with infestations. Hummingbirds and dragonflies are also natural predators!

Preventing Whiteflies

Tiny whitefly on fingertip. Source: davidshort

Place new plants in quarantine for a couple weeks. I know, it’s difficult to do, but before adding new plants to your garden or your greenhouse, keep them separate and observe them for a little bit. That way, if you develop problems with hidden pests, you’ll be able to deal with them fast. And you won’t introduce the whitefly infestation to your other plants!

Using neem oil on your plants will deter whiteflies from laying eggs on them. In addition, the oil will coat the eggs and larvae and smother them. Be sure to thoroughly coat both the bottoms and tops of the leaves as well as their stems for complete coverage.

Try mulching with a reflective mulch fabric. Reflective fabrics are confusing to whiteflies, and they tend to leave those plants alone.

To gauge if you’ve got a whitefly problem, use yellow index cards coated with petroleum jelly. Set them around your plants. While these aren’t as effective as yellow sticky traps, they also can catch white flies and alert you to their presence.

Use Tanglefoot Tangle-Trap around the base of citrus trees that develop whitefly infestations. While this sticky gel will not catch many of the white bugs themselves, it will stop ants from getting into the tree.

Ants can farm aphids and whiteflies for the honeydew secretion that they produce. They’re known to protect their honeydew providers from natural enemies. If you reduce the ants in your plants, you can reduce the spread of your whiteflies!

Whiteflies on plumeria. Source: Scot Nelson

Frequently Asked Questions

Q: Do whiteflies bite people?

A: Unlike the irritating black flies (sometimes called horseflies) that bite, whiteflies are harmless to people. They’re just not attracted to humans or our pets or livestock. Whitefly damage is found on plants only!

Q: How can I deal with whitefly honeydew on my plants?

A: Great question! The white fly releases a sticky secretion called honeydew. Left in place, this honeydew can develop black mold that can inhibit plant growth. A good spray of water should wash it away.

If black mold has formed, you may need to wipe off the mold with damp towels. Once you’ve removed the majority of the mold, spray the plant down thoroughly with neem oil, which should prevent further mold growth.

Are you ready to be rid of this white and annoying menace to your plants? I know I am. Whiteflies are horrible to deal with! Have you used any other techniques in the war against these tiny white flies? Let us know in the comments below!

The Green Thumbs Behind This Article:
Lorin Nielsen
Lifetime Gardener
Kevin Espiritu
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What Are Those Tiny White Bugs on My Plants?

Many common garden and greenhouse pests are so small that they appear to be nothing more than tiny white dots. But these bugs can cause serious damage to your plants. If you have noticed white insects on any plants in your garden or home, it is vital that you work out what they are and how to get rid of them!

So, what are those little white bugs on your plants?

Most likely, these tiny white bugs are one of three things: whiteflies, spider mites or mealybugs. And because of their size, it’s extremely difficult to tell them apart and tell which small white bug is which.

Luckily, we’re here to help! Continue reading this article to find out more about three of the most common white bugs that are found on plants, how to tell them apart and what to do about each of them.

Whiteflies

Catherine Eckert/.com

The whitefly is a tiny, winged insect that sucks sap from the leaves of a wide variety of plants. They are typically found on the underside of the leaves of many species of vegetables, flowers, and fruits. Whiteflies can be found in greenhouses and among outdoor crops. You may even find these tiny white flies in your house, where they often attack potted plants.

There are many different species of whiteflies. The problem is that they look so similar to one another that it can be very difficult to tell them apart. Measuring about 1/16 in. (1.5 mm) in length, whiteflies are tiny, white, and have a moth-like appearance. A whitefly infestation is easy to spot, though. You simply have to give the stems of your plants a shake to see these insects rise up in a white cloud.

What plants do they live on?

Whiteflies inhabit and feed on a wide variety of plant species. They especially like greenhouse crops. For that reason, they are most commonly found on tomatoes, peppers, lettuce, hibiscus, petunias, cucumbers, eggplants, fuchsia, squash, geraniums, begonias, chrysanthemums, potatoes, and many more!

How do they damage plants?

Whiteflies cause serious damage to the plants they feed on. These sap-suckers pierce the leaves of plants, causing yellowing, spotting, disfigurement, wilting, and the premature dropping of leaves. In the case of large infestations, a whitefly invasion can even lead to plant death.

As if that were not enough, whiteflies also produce honeydew. This is a sticky, sugary substance that coats foliage and encourages the growth of a sooty mold. This black fungus can cover leaves and, in extreme cases, inhibit photosynthesis. Worst of all, whiteflies can also transmit several viral diseases to their host plants. These diseases can stunt growth and inhibit the production of fruits and vegetables.

How can you get rid of them?

Whiteflies are a persistent pest that can be tricky to get rid of. There are, however, several ways you can battle these bugs.

Use reflective paper or plastic mulch in plant beds as a protective measure. Place sticky pads near plants to trap whiteflies before they can land. If you already have a whitefly infestation, try spraying the leaves of plants with a high-pressure hose to physically remove the insects and their eggs. Insecticidal sprays may also help to eradicate whiteflies. Or, if you prefer a natural approach, these pests have several natural predators that can help to keep their numbers under control.

Spider Mites

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Spider mites are a tiny arachnid that is commonly found in gardens, houseplants, and greenhouses around the world. Measuring just 1/50 in. (0.5 mm) in length as adults, these bugs are so small that you may miss them. Spider mites do produce a fine, silken thread, though, that can give leaves a cobwebbed appearance. This can make a spider mite infestation easier to spot.

These pests vary in color. For example, the two-spotted spider mite can be white, orange, red, light green, or dark green and sports a pair of black spots on its abdomen.

What plants do they live on?

Spider mites can live on hundreds of species of plants. In particular, keep an eye out for them on your cucumbers, tomatoes, lettuce, peas, beans, strawberries, blackberries, blueberries, azaleas, marigolds, roses, and even trees like maple and elm.

How do they damage plants?

Like whiteflies, spider mites are sap-sucking bugs. While small numbers of mites will probably not cause any noticeable damage, a large infestation can spell trouble for your foliage. Feeding can cause tiny white or yellow speckles to appear on leaves. Over time, this can give the leaf a discolored, mottled appearance. In the end, the leaves may drop prematurely while heavily infested plants can become stunted or even die.

How can you get rid of them?

You can identify spider mites by shaking the leaves over a sheet of paper. If the plant has mites, you will be able to see them walking slowly across the paper.

One of the best ways to remove spider mites from plants is by blasting the leaves with a jet of water, physically removing them. These bugs also have several natural predators. You can purchase and release these predators on infested plants to naturally control the spider mite numbers.

If all else fails, consider treating the foliage of any affected plants with a soap spray or a selective miticide to effectively reduce the population.

Mealybugs

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If you own a greenhouse, those white dots on your plants could well be mealybugs. These tiny, segmented insects measure between 1/20- to 1/5-in. (1-5 mm) in length and are covered in a waxy, white coating. Mealybugs tend to hang out in clusters around inaccessible parts of the plant, such as leaf axils, sheaves, between fruits, between twining stems, and some even colonize roots.

Many mealybug species also attack house plants. Be on the lookout for a white, cottony substance on the leaves, stems, and shoots of plants. This is often the first sign of mealybugs.

What plants do they live on?

Mealybugs invade many different species of greenhouse and indoor plants. They are often found on tomatoes, peaches, bamboo palms, cacti, succulents, orchids, grapevines, citrus trees, jade plants, hoya, ficus, fuchsia, palms, poinsettias, begonias, and strawberries, among others.

How do they damage plants?

Small numbers of mealybugs may not cause any noticeable damage to plants. Large infestations, however, can weaken and even kill host plants.

This is because mealybugs are sap-sucking insects that drill into the foliage as they feed. This causes distortion of leaves, stunted growth, and reduced numbers of flowers, seeds, and fruit.

Like whiteflies, mealybugs also produce honeydew, which can lead to sooty mold that can quickly cover foliage. It reduces the attractiveness of plants and, in extreme cases, prevents sunlight from reaching the leaves.

How can you get rid of them?

Mealybugs are notoriously tricky to get rid of. This is due to their waxy coating and their annoying habit of hiding in the hard-to-reach parts of the plant.

The best way to remove mealybugs from your houseplants is to do so manually, using a cotton swab soaked in rubbing alcohol. This will dissolve their waxy coating, thereby killing the bugs. It, however, can be time-consuming.

Natural predators and parasites can provide good control. Insecticides aren’t very effective, but insecticidal soaps or oil sprays are good options. Like other small pests, a jet of water can dislodge them.

Conclusion

Many garden, greenhouse, and house plant pests may simply appear to be little white bugs on the leaves. While their small stature may make them difficult to tell apart, their potential to cause damage is not to be underestimated!

If left unchecked, pests such as whiteflies, spider mites, and mealybugs can devastate plants. They can form large infestations in vegetables, fruit trees, and ornamental plants that are almost impossible to get rid of. Learning to correctly identify these insects and the first signs of the damage they cause is vital to protect your plants from these pests.

Aphid control in peppers

Aphids are serious pests of peppers. Colonies are capable of phenomenal growth, and a single pepper plant or whole crop can be devestated seemingly overnight. As soon as an infection is noticed it should be dealt with – never delay and hope the aphids will go away, they won’t.

Aphids are small, oval-shaped sap-sucking insects. They normally have a green body, but they can be black – hence the common names “greenfly” and “blackfly” – and some species also occur in a red form. A large number of species are found in British gardens, and 14 of these have been identified on chilli and sweet pepper plants. However, three species are particularly common on pepper plants. The most widespread of these is the peach potato aphid (Myzus persicae). This species has a plump oval shape, and the adults are up to 2 mm long. They are normally green, but red versions do occur. Becoming increasingly common is the potato aphid (Macrosiphum euphorbiae). This species has a large (1.7–3.6 mm) and slender body, most are green and some may have a darker green strip running down the centre of their back. And finally, there is the glasshouse potato aphid (Aulacorthum solani), another large aphid measuring 1.8 – 3.0 mm.

Peach potato aphids (Myzus persicae) on the underside of a chilli pepper leaf.

The life cycle of an aphid

Aphids have a complicated life cycle, which includes both sexual and asexual reproduction, viviparous (giving birth to live young) and egg laying adults, and winged and unwinged forms. For the pepper grower it is important to understand how the pests overwinter, but a detailed understanding of their life cycle is only essential over the growing season.

In Britain the three main aphid species that attack peppers are polyphagous (feed on many different plant species). As long as temperatures are suitable, they may remain within the polytunnel or greenhouse residing on whatever plants are available – which often means using overlooked weeds. They also overwinter outdoors on whatever alternative host suits that particular species. For example adult peach potato aphids lay eggs on twigs of peach, plum and other related species.

During the growing season most greenhouse aphids are female and do not need a sexual encounter to reproduce. They do not lay eggs, but rather give birth to live young that are a perfect, though small, replicate of their mother. Not only are these newborns fully functional sap-sucking pests, but they are also pregnant – they actually have young developing inside them as they are being born themselves. In warm conditions the young aphids take about a week to grow and mature, before they too start giving birth to live, pregnant young.

Each aphid will give birth to about three to ten young every day for up to four weeks. Given these figures, in good conditions aphid populations can grow at alarming rates. When a grower notices signs of aphids on a pepper plant they should be dealt with immediately. If left alone it will not be long before there are thousands of aphids, and then hundreds of thousands.

The majority of aphids in a population are wingless, and they spread simply by walking from leaf to leaf and plant to plant. However, under certain conditions, particularly overcrowding, some aphids are born with wings. These can then fly away and infect a new plant elsewhere.

Damage caused by aphids

Aphids cause damage to the plants in several ways:

First and foremost, they weaken the plants by sucking the plant’s sap. Sap, a sugary solution that is passed around the plant, is the plant’s food, and any loss will reduce growth.

Secondly, as the aphids suck up large quantities of sap, they have to excrete the excess, which is a sticky solution called “honeydew”. The falling honeydew lands on the leaves and fruit below, which causes problems for the plants in two ways:

  • The honeydew is sticky, and when it covers the leaves they collect dust.
  • The honeydew is very sweet which attracts sooty mould growth, making the leaves turn black.
Black sooty mould growing on pepper leaf growing on honeydew dropped by aphids.

The effect of the dust and black covering of sooty mould on the leaves is to reduce the amount of light reaching the leaves. Without light photosynthesis cannot occur. Photosynthesis is the process within the leaves that makes the plants’ sugars, and is essential to the health and growth of the plants. In serious infestations little light reaches the leaves and photosynthesis will virtually be stopped.

The falling honeydew also makes the pepper fruit sticky and turn black, making them unappetising to the home grower and worthless for selling.

However, this is not the whole story; aphid saliva is also bad news for the plants:

  • It contains toxins that cause the emerging leaves to be deformed. This happens more with the glasshouse potato aphid than with the other species.
  • It carries viruses, and an aphid feeding on an infected plant will transfer the virus to all other plants it feeds on.

Symptoms

Aphids congregate within the young leaves in the growing tips of peppers and on the underside of the mature leaves. This means they are well hidden, and go unnoticed when infestations are at an early stage. However, there are certain tell-tale signs that indicate their presence:

  • Distorted leaves emerging from the growing point.
  • Scattering of white skin casings under the plant.
  • Ants actively running over the plant.
  • Sticky leaves. In addition, the area around the plant can get sticky.
  • Leaves turn black from sooty mould.

The fallen white skin casings are a very clear sign of aphids; they are also the cause of a very common misdiagnosis. Young aphids shed their skins as they grow. Generally each juvenile will shed its skin four times before it reaches maturity. These skin casings fall to the leaves below, and as they dry they turn white. Many growers see these white forms on the plant and assume they have a whitefly problem. Though whitefly can attack peppers a serious infestation is rare – after growing chillies commercially for 22 years we have never had a whitefly problem on our peppers – even though we do regularly get whitefly on our tomatoes in neighbouring polytunnels.

A simple test is to shake the plant. Whitefly are literally white flies, and if the problem is whitefly the adults will fly up when the plant is shaken. Most aphids are wingless, and a hard shake may make them fall off, but they certainly will not fly.

Ants are often found near aphid colonies as they feed on the sweet honeydew. To protect their food source ants actively look after, or “farm”, the aphids, protecting them from insect predators.

Sticky leaves and sooty mould on the leaves are symptoms that occur when an infestion has become well established. For many growers the early tell-tale signs are harder to notice so these are often the first symptoms noticed. However, these symptoms will affect the plants’ ability to grow and immediate action to control the aphids is essential.

Control

An aphid infestation must never be ignored. Aphids can be controlled quite easily, but it is an active process, they will not go away by “forgetting” they are there.

There are three approaches to control for a home chilli grower:

  1. Biological control
  2. Water
  3. Pesticides
Biological control

There are several insects that prey on aphids. The species that most gardeners are familiar with include:

  • Ladybirds
  • Lacewings
  • Hoverflies
  • Parasitic wasps

Ladybird larvae enjoying an aphid meal.

Many of these “good guys” occur naturally in the garden, and a gardener should do their best to encourage them. It is well worth a gardener learning the life cycle of these insects, but most importantly, becoming familiar with what they look like. Of course, most people, easily recognise the adult stages of ladybirds, lacewings and hoverflies, but very few gardeners know what the eggs, pupa and juvenile stages of these species look like. An hour on the internet can easily remedy the situation, and would probably be one of the most valuable hours spent on the garden!

Adult hoverfly

Ladybird larvae (left) and pupae (right) on a chilli pepper leaf.

Most outdoor areas will have some beneficial insects in residence that will maintain some level of aphid control without the gardener ever knowing. However, the indoor environment of a windowsill is unlikely to have any insect predators occurring naturally, and chilli plants kept indoors as a house plant will have no defence against an aphid infestation. Still it never hurts to bring in any ladybird found outdoors to reside on a favourite plant!

Adult and juvenile ladybirds eating aphids on fathen, an outdoor weed.

As well as maintaining an envirionment that encourages the presence of naturally occuring insect predators, it is possible to buy-in predators and parasites. These are sent out through the post, and once released into the polytunnel or greenhouse, will provide aphid control and bred themselves thus increasing their populations. Though not cheap this is the method recommended for all gardeners with plants in a polytunnel or greenhouse.

For the home gardener and small commercial operations we recommend Agralan (www.agralan.co.uk), a company that is dedicated to protecting crops through biological control. For large commercial growers whose orders will satisfy the minimum order restrictions, there are a number of companies that provide a complete control programme through biological control.

Releasing parasitic wasps into a polytunnel with a chilli pepper crop.

Left: aphid mummies formed by the parasitic wasps laying an egg in the aphid.
Right: a single aphid mummy with with a round hole where the parasitic wasps escaped.

Releasing commercially bought ladybird larvae into a crop of Hungarian Hot Wax chillies.

Growers who take their chilli growing very seriously are recommended to start buying in predators before they see any signs of aphids. This army of “good guys” will seek out the aphids and deal with them long before even an alert grower is likely to find them.

The mantra to follow for biological control is that it is a “numbers game”. If there are enough beneficial insects, aphids will be controlled. If predator numbers are too low, the aphid colonies will grow. The later you start using biological control the more predators or parasitoids will be needed.

Unfortunately, insect predators are not a realistic option if you keep just one or two chilli plants on a windowsill in the house or conservatory. See below for more information on controlling aphids on house plants.

  • Water

Prevention is always better than cure, and the predator option is undoubtedly the best method of aphid control. However, if an infestation does occur it means there has been an imbalance between predator and aphid populations, and a more proactive control method is necessary. In other words, once an infestation has become established, whether it is on a single plant in the house or in a large commercial greenhouse, will not clear up on its own, the plants will not recover without an intervention.

Before resorting to pesticides we recommend trying water as a control method. Water is safe, effective and because of the sticky honeydew, aphid-infected plants will always need to be washed down anyway. Aphids do not hold on tight and a blast of high pressure water – a finger on the end of a hosepipe or the cold water tap on full – will knock them off the plant. Most effort should be applied to the growing points and the underside of the leaves as this is where the aphids congregate. If the plant is in a pot lying it on the ground or turning it upside down will give full access to under the leaves. Water does not kill aphids and they will readily walk back onto the plant. So if the plant is in a pot do not wash it near where it is normally kept and wash down the area before returning it to its place. If the plants are in the ground this is not so easy, but if it is possible wash/brush down the area as well as the plant.

It is unlikely that one wash, no matter how thorough, will remove all the aphids. So to get a complete control repeat the operation the next day…. and the next if necessary. Some customers say washing doesn’t work; most likely the failure was due to a half-hearted wash; a thorough wash means THOROUGH.

  • Pesticides

Pesticides are substances or a concoction of substances that kill pests. They can be either natural or synthetic and they work in different ways; some are potent poisons, others cause death through a physical process. Some have very specific target pests, others are generalists and an application will have a universal kill. All should be used carefully and with a full understanding of how to use the pesticide and the objective of the application.

When buying a pesticide always read the label. Be sure it is recommended for use on peppers, and if you keep the plant in the house, it must state that it is suitable for “houseplants”. In addition, the pesticide must state it is to be used to kill aphids (the packaging may say “greenfly” or “blackfly”); remember whitefly is not another name for aphids. All retail stores selling garden pesticides to the home gardener must have someone at the available who can advice you on the use of pesticides. Commercial growers are governed by different laws, they can buy stronger pesticides from suppliers that are unavailable to home gardeners, but now must take specific pesticide application courses and then be registered.

Chemical pesticides: These are powerful, toxic chemical pesticides can be bought to kill aphids. A perusal in any garden centre will reveal a whole host of brands available to the home gardener. Many are systemic, which means they work by being absorbed into the plant so the aphids are killed when they digest the poisoned sap. Unfortunately, these pesticides (poisons) will be transported throughout the plant, including the parts of the plant we eat. It is essential the instructions are followed carefully, including the withdrawal period, i.e. the time that must elapse between applying the pesticide and consuming the peppers picked off the plant. The plus side of systemic pesticides is that they specifically target the sap-sucking pests. However, you should check the compatibility of individual pesticides with natural predators as some chemicals can kill natural enemies for up to 8 weeks (check the biopest side effects list).

Physically acting pesticides: There are several compounds that are relatively benign to the environment and humans. They work through a physical action taking advantage of the insects’ small size or physical shape. Many are so safe they are considered acceptable for organic growers. A common active ingredient is a fatty acid, but there are others, e.g. SB Plant Invitorator, which kills simply through a physical action – the packaging states: “aphids, juvenile whitefly and spide mite if directly hit are trapped by its wetness”.

A search on the internet will reveal several companies that sell these pesticides, but the one we recommend is: www.harrodhorticultural.com

As these pesticides work through a physical action they can only be effective when a 100% coverage is achieved – this is so important the instructions on some state the liquid should be applied until it drips off the plant.

Applying Eradicoat, a sticky solution made from cornflour, to kill a bad infestation of aphids on a poblano chilli crop.

Unfortunately the physically acting pesticides kill all species of small insects and mites, including the beneficial species. Consequently, where beneficial insects are present in a crop it is often recommended to only apply the pesticide where the aphid colonies are worst. More beneficials can then be released as soon as the crop has dried after spraying physical products as there are no residual effects.

Dead aphids after an application of Eradicoat; the “aphid mummies” are not hurt by the Eradicoat.

Some people make up their own home-made concoction to kill aphids. A common one is diluted washing up soap. Washing up liquid contains many more chemicals than just soap, some of which are bad news to a growing plant. So while such a solution may kill the aphids it may also kill the plant. In addition, under UK and EC law it is illegal to use any home-made mixture as a pesticide – the law states only preparations approved as a pesticide can be used specifically to kill pests.

The chilli plant as a house plant

Certain chilli species are very attractive when grown in pots, and as they like the warm, sunny conditions typical of a sunny windowsill or conservatory they do make excellent houseplants. Unfortunately, chilli house plants are not spared the risk of an aphid infection. As aphids reproduce asexually it only takes a single aphid to get into the house – maybe a winged one through an open window or possibly hitching a lift on a human or pet – to start an infestation. The home environment does not encourage the presence of natural preditors, so once an aphid colony has become established it is likely to grow at a frightening speed and quickly destroy a plant.

Chillies make very attractive houseplants.

As a precaution it does not hurt putting ladybirds on a chilli house plant as they will seek out and eat any aphids that arrive. However, once an indoor plant is infected the best thing is to give the plant a thorough wash. It is unlikely all the aphids will be removed by a single wash, so repeat the wash every day for the next three or four days.

Summary

All pepper growers will experience an infestation of aphids on their plants at some time in their growing career. There is simply no way of avoiding the pest, and anyone who has not had a problem with aphids just haven’t YET had a problem.

But an aphid invasion is not the end of the world. Do not throw away your precious house plant – as some people do. Nor should you allow the aphid population to continue to grow. Deal with the aphids and reclaim the health of your plant.

  • Knowing and recognizing: The biology of glasshouse pests and their natural enemies. M.H. Malais and W.J. Ravensberg. Published by Koppert B.V. ISBN: 90 5439 126

Thanks to Clare Sampson, consultant entomologist for BCP Certis., for reading this article and checking for accuracy.

© Joy Michaud

Whitefly Infestations on Chilli Plants

Every year spent growing chillies seems to throw up a different problem. Too cold, too changeable, not enough sun, too much rain….there’s always something getting in the way of the perfect growing season. I suppose that’s the attraction of gardening…pitting your horticultural skills against the unpredictability of nature.

This year the main problem I’m facing with my pepper plants is whitefly. We’ve talked before a few times about aphid infestations and how to deal with them but to date we’ve not really covered whitefly in much detail.

Having got back from a short holiday I discovered a big whitefly infestation in the chilli house. As with all garden pests it’s usually so much easier to deal with the problem if you catch it early.

Whitefly feed on the plants sap which is why they tend to attack the fresh young growth on plants. Left unchecked they will multiply rapidly and cause lasting damage to the host plants, often stunting their development.

The whitely also secrete a sticky residue on the plants which then attracts dust and muck and usually causes problems with fungal growths on the leaves.

Plant Marigolds In With Chillies

In the past I’ve planted French Marigold into pots and kept them in the chilli house. Marigolds are a natural deterrent to aphids and whitefly and I’ve had some success with this method in the past.

Having a full time job with long hours means that I try to avoid pots as much as possible as I spend all of my evenings watering if I’m not careful. In addition planting marigolds in small pots means they tend to dry out very quickly on hot days which isn’t ideal.

I grow most of my chilli plants in Quadgrows or my DIY self watering pots which saves massive amounts of time watering. I don’t know why I’ve never done it but next year I’ll try planting one French Marigold in each self watering pot. This way there’ll be no extra watering involved or extra space taken up by the marigolds.

Lady Birds

If you’ve got kids around the house then they help is at hand. Send them out lady bird hunting – they usually don’t need much encouragement. Ladybirds are phenomenal for their ability to eat their way through a whitefly infestation so if you can catch a few and release them onto your infested plants they will make a material difference.

Fresh Air

If the infestation is really bad I find the best/easiest method is to move all of your plants outside. By doing so you’ll let the natural predators in the garden go to work on the whitefly. This typically clears the problem up in 2-3 days. While the plants are outside be sure to give the greenhouse a thorough clean to ensure any larvae are removed.

Once the plants go back in to the greenhouse always try to ensure you have as many windows/doors open as possible (temperatures allowing). This will ensure natural predators can get in and keep your plants clean.

Traps

According to the Colorado State University whitefly are attracted to yellow things. This means that using sticky fly traps n the greenhouse is a great method to catch mature whitefly. Personally I’m not a big fan of using these traps as they tend top trap ‘good’ insects too (hover fly, lady birds etc). That said if you have a bed infestation and moving the plants outside (see above) isn’t an option then using sticky traps to get it under control can be a good option.

Cleanliness

One key method to prevent pests and disease in the greenhouse (including whitefly) is to keep things clean. By regularly removing any dead plant matter, spilt compost or other organic matter you’ll be removing habitat that pests like. I also try to regularly wipe down shelves, windows and tables with warm soapy water to improve sanitation.

Insecticides

If you have to use insecticides then make sure they are based on pyrethrins (permethrin being the most common). Neem oil sprays are also highly affected.

Protect Your Greenhouse Plants from Whiteflies

Whiteflies can wreak havoc in your greenhouse. These little soft-bodied greenhouse pests multiply so quickly they can take over your greenhouse before you know it. They suck the juices from your plants causing leaves to turn yellow or fall off the plant. White flies secrete honeydew, leaving a sticky coating on the leaves of your plants. It is important to monitor your greenhouse carefully to control these garden pests. Once you have in infestation, you have to act quickly to save your plants.

A useful way to monitor the whitefly population is to use yellow sticky traps. White flies are attracted to the color yellow. The traps can be made by using yellow poster board and applying a sticky substance such as axle grease. Punch a hole in the poster board and hang the traps with string near the infested plants in your greenhouse. Re-apply the grease when the traps loose their stickiness. The traps alone won’t be enough to control a white fly infestation, but it will help you to realize when their population is multiplying.

One effective and all natural way to combat whitefly greenhouse pests is to apply insecticidal soap. You can make a homemade insecticidal soap concoction or purchase a commercial spray such as Flower Pharm insecticidal soap to eliminate the bugs.

Try making your own insecticidal soap with a recipe of one gallon water, 2 t baking soda, 2 t dish detergent, and 2 t white vinegar. Spray the pest treatment under the leaves of your plants where the white fly eggs, scale and adults reside. This can be time consuming as the bugs will die only when they come in direct contact with the spray. Each leaf needs to be sprayed. You must be diligent and apply the spray every 3 to 5 days to maintain control over the white files. Use soaps when plants are not drought-stressed and when temperatures are under 80°F to prevent possible damage to plants. Test the insecticidal soap first on your plants to make sure it will not burn the leaves. Spray the soap on a few leaves and wait two days to see if there is any burning. If burning occurs, try diluting the spray with more water and test again. Insecticidal soap is very effective on controlling white flies and many other greenhouse pests. The drawbacks are it can also kill the good bugs and it is generally a big time commitment.

An alternative to the time commitment of spraying insecticidal soap is to use beneficial bugs as in your greenhouse. A very effective beneficial insect for eliminating white flies in the greenhouse is Encarsia formosa. This tiny parasitic wasps sting the whitefly scale and deposit there eggs inside the whitefly. As the wasp offspring develop, they eat the white fly from the inside out. The Encarsia need warm temperatures of 65 to 80 degrees so you may be limited to using Encarsia only during late spring and summer. Green lacewings and ladybugs also feed on whitefly and other bad bugs. You can order both of these bugs through mail order programs. It is best to set up a program to receive the bugs in regular intervals for a couple months to get a handle on any infestation. Avoid using sticky traps and insecticidal soaps when releasing beneficial bugs so you don’t kill off your investment.

As a final note, make sure to wash off any sticky honeydew residue left behind on the leaves of your plants to prevent disease.

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Plant Problems – Aphids & Whiteflies

What Can Be Done
There are several things you can do to try to get rid of aphids and whitefly but they can be a difficult pest to deal with once an infestation has got out of hand. Here are a few methods we have tried and the results they bear.
1. Spray with water with a dash of washing up liquid. This may have some impact of larvae and flies but little or no consequence on the eggs, making it a cheap but not very effective method.
2. Derris dust has traditionally been used by organic gardeners and has some effect on low level infestations of chilli plants. However, we would not recommend using this as the product is about to become outlawed Europe due to links to Parkinsons disease.
3. There are a number of greenfly sprays available from your local gardening shop if you decide to go down the non-organic route. All of these are near useless for aphids and whitefly and will tell you so on the back of the bottle.
4. The only pesticides really found to be of use in severe infestations are those containing Permathrin. However, you will not longer find this chemical contained in sprays for edible plants. We have had some success with Permathrine fumers (Fortefog greenhouse fumer) which are akin to a little candle that fills your greenhouse with a toxic smoke. This is better for your plants than spraying directly onto them, but not a suitable method if you have fruit on plants that you want to eat.
4. Biological solutions are also available and these can be effective in prevention as well as cure. These are often used by different commercial greenhouse growers. Most effective is a combination of Aphidus – a parasitic wasp that lays eggs into immature aphids and Aphidolites, whose larvae voraciously feed on aphids. You can buy these biological pest controls from Defenders. However, this is not a cheap method and if you are using biological controls, you obviously cannot use any other controls as you will kill the killers as well as your problem pests.
5. Diatomaceous Earth is sometimes known as Fossil Shell Flour. It is a silica-like substance that has oceanic origin. It is actually make up of millions of tiny shell particles which, although it doesn’t feel it to us, are razor sharp and cut into the exoskeletons of insects. Diatom is routinely used by poultry farmers to prevent and control mite infestations and there are food brade variants that can be swelled to deal with internal parasites too. It’s inert and organic. Pop a teaspoon into a sieve or teastrainer and gently tap into the growing tips and crowns of plants or wherever you can see larvae. You will very quickly notice that where there is Diatomaceous Earth, there are no critters.

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