Get Rid of Orchid Scale Once and For All

Author: Celeste Booth

Care and Culture, Insects

There are not many pests that can severely damage an orchid collection, but along with mealybugs and aphids, scale is one of orchids’ biggest pests. It is a small insect that can devastate a collection of orchids. A small infestation will result in marred areas on the leaves and large infestation can kill the whole plant. The process to remove them can be complicated but early detection and careful management can prevent the destruction they can cause.

Different Types of Orchid Scale

There are 27 varieties of scale and two main types, soft scale and hard scale. Scale range in size from one to five millimeters and, in certain life stages, can be difficult to see without magnification. Male soft scale appears grayish to white and can look similar to mealybugs. Soft scale damages the plant by sucking sap from the plant. It also leaves behind a sticky excretion called honeydew. Hard scale does not leave this excretion. A large infestation of males will appear powdery and white. Adult females create larger scales that protect eggs. Soft scale can be found along the underside of leaves, along the stem, and even in the roots and rhizomes. Cattelyas are particularly susceptible to a type of brown soft scale called Boisduval scale. Boisduval scale often appears on the undersides of leaves along the midribs and underneath the sheaths. It occurs naturally outdoors in California and Florida, but can appear in greenhouses in any climate. Hard scale is rarer on orchids, but can be identified by its hard brown domes of the adult female.

The Life Cycle

The life cycle of scale is very brief. Scale moves from eggs, to the nymph stage called crawlers, to adults in the matter of a little less than two months, and there may be several generations of scale within a year. These cycles are fastest in an indoor or greenhouse environment. As a result, management, once orchids have been infested, is very difficult. The caretaker must be very persistent in his or her approach and must apply treatment at least every ten days. If you have been using the same treatment for more than a few months and still have scale problems, you must switch treatments as some of the scale may have become immune. The scale is most easily treated during its crawler stage, this is also the stage when it moves between plants. The last stage of the life cycle for a female scale is when it hardens and lays eggs under the protective covering that it is named for. Once the eggs are laid and the shield is hard the scale dies.

Prevention

-Scale

The easiest way to avoid a scale problem is to stop it before it starts. Scale spreads easiest from plant to plant, and occasionally on air currents. So, it is likely that a scale problem come from a new plant that is introduced to a collection. Be sure to inspect any new plants and even quarantine them for two weeks to see if any evidence of scale appears, because not all stages of scale are visible to the naked eye. If scale does appear, you can treat this plant separately and avoid introducing scale to the whole collection. If you notice scale on a plant you already have, quarantine it right away, while you are treating it, and a short time after to make sure it doesn’t reappear. This should hinder the movement between orchids. Movement will also be stopped between orchids if leaves from different plants are not allowed to touch one another.

If you keep your orchids outdoors, you will also have some assistance from natural predators and parasites. Ladybugs like to eat soft bodied insects and will eat scale. Wasps can also lay eggs inside the hardened scale, they will then feed off the scale eggs and emerge as adult wasps, effectively killing the scale in their first stages of development.

Treatment

For a small infestation, you can rub the scale with isopropyl alcohol on a cotton swab to remove them. This can be hard on the plant, so don’t do it too often or if there a large amount of scale. There is also the possibility of chilling the plant with the fast evaporating alcohol. You may want to wipe away extra alcohol from the leaf so that it doesn’t damage the leaf tissue, especially if the plant is in windy location. If you can, move the plant away from any air currents. Another option for management suggested by the Canadian Orchid Congress, is to carefully wash the whole plant in warm water with grated soap (be sure the soap is mild and not ammonia-based, as this will cause damage to the plant). The plant must be washed every other day for a month. Then it must remain separate from other plants for two weeks to ensure no new scale appears.

The next level in treatment, if the previous two home remedies do not work, is to use horticultural oil. This oil must be applied thoroughly to the orchid. Scale hides well in the sheaths, along the base of the plant, and both the top and bottom of the leaves. It can be easily missed and infest the plant again. The oil works by smothering the scale, so any surface that is not covered will not be effectively treated. The oil can burn the plant’s leaves if used on a hot day or in direct sunlight. Take care to keep the orchid shaded during treatment. Also, take care to follow the directions on the labels very carefully so that you do not damage the plant.

Orchid and Beetle

Finally, if the horticultural oil does not take care of the problem, you may have to use chemicals. Some insecticides are available for use on orchids. Make sure they are labeled for use on ornamental plants, and seek help from a technician if you are unsure if the chemical combination is safe for your orchids. Always follow the label carefully and do not use a concentration any more or less than suggested, too little may be ineffective and too much will kill the plant. Remember that insecticides can be harmful to people and pets. If you cannot spray the orchid outside because of weather, place the plant in a large plastic bag and then spray it. Once the spray has settled, remove the bag and place the plant in an area away from any air currents.

If your plant has had a large infestation you may have scale in the roots. If this is the case, remove the orchid from its container, and shake all of the old growing media loose. You can wash the roots, or if you are using an insecticide, spray the roots. Then repot the plant in a new, clean container with new growing media.

Care tips to remember

Remember, as you care for your orchids, that scale can be devastating and any measures you take as a precaution against it are worth the extra effort.

  • Always quarantine new orchids for two weeks before displaying with your collection.
  • Check all of the orchids in your collection regularly for signs scale and remove potential problems immediately.
  • Keep plants separated and do not allow leaves of different plants to touch one another.
  • Once plants have been treated for scale, keep them separated from your collection for two more weeks to ensure the treatment was successful.

If you are battling a scale infestation, be sure to stick with the treatments, repeating them about every ten days. With your persistence and care your orchid collection can be kept scale free and beautiful.

Oregon Orchid Society

Cottony Scale

In the Pacific Northwest, scale and mealy bug are notorious attackers of orchids. There are thousands of species of scales and mealy bugs but they are all close relatives, hailing from the order Homoptera (along with aphids). Four distinct families make up the scale/mealy bug section (aka, the “superfamily” Coccoidea) :

  • Coccidae – soft scales
  • Diaspididae – armored (or hard) scales
  • Margarodidae – cottony cushion scale
  • Pseudococcidae – mealy bugs

All of these families of scale and mealy bug can be found in the Pacific Northwest and can be detrimental to the health of orchids but one strain of scale is of particular note since it is the main nemesis of orchidists: Boisduval’s scale (Diaspis boisduvali). This form of scale is NOT from the Pacific Northwest but has spread from tropical America via commercial trade to infest orchid collections around the world.

Male Boisduval Scale

A confusing factor in identification of any scale is that they have different stages to their development and it is important to be able to recognize those stages. Scales are so called because they have a stage in which they are under a hard protective shell that sits on the leaves or pseudobulbs of the plants. This is done when the female is producing eggs. After the eggs have been laid under this hard shell the female dies but in due time the shell will break open and the eggs will hatch. Treatment in this stage is very difficult.

After the scale stage there is a massive explosion of nymphs because under one scale are thousands of eggs. Making things even more difficult for the orchid grower the motile scale insects actually have wings and, while they are not good fliers, they can travel from plant to plant. If you’ve been good to your orchids you’re also giving them some decent air movement – but this can also serve to spread scale throughout your greenhouse. If left untreated scales (and mealy bugs) will destroy an orchid collection and easily become untreatable without drastic measures.

Young Scale and Female Scale

Scales reproduce in exponential numbers and the rate of reproduction is accelerated in a warm greenhouse setting. It is imperative that the minute you see any sign of scale on your orchid(s) that you treat it.

In the crawler stage insecticides will kill some scale, but their sheer numbers will likely make your efforts in vain. A multifaceted approach that includes insecticidal soaps and horticultural oils, which smother the crawlers, is needed and should probably be used as a preventative.

Also, pay attention to the dark crevices on your plant as well as the undersides of the leaves. These bugs like to reproduce in the darker, cooler spots. When plants are crowded there are more dark places with stagnant air so a good preventative measure is to keep ample space between your plants.

Scales and mealy bugs are fond of certain orchids and the Boisduval scale was probably introduced to temperate regions via their favorite hosts: Cattleya alliance orchids. Some orchids seem to be impervious to Boisduval scale, but weaker non-Cattleya alliance orchids can succumb to infestation if the scale population is not controlled.

If you have a scale-infected plant, you should quarantine it. It is wise to treat the infected plant with alcohol (item 1 below) and to follow up with your whole collection, including the infected plant, with items 2 and 3.

Treatment Details Indoors?
Isopropyl Alcohol Spray any visible scale (in any stage) with a mixture of rubbing (isopropyl) alcohol and water with a few drops of dish soap included as an emulsifier. 60-80% water should be an appropriate amount. Spray the scale directly and use cotton swabs to rub off the pest. Hard scale may take extra effort in this regard, but the alcohol should loosen or dissolve the shell. Don’t soak plants in alcohol for extended periods of time as this will dehydrate the plant and kill more sensitive plants. Safe indoors but labor intensive. Doesn’t get to scale in the nooks & crannies of the plant.
Systemic Use a good systemic on the plant and in its water. A good chemical to look for is Imidacloprid, which is a chlorinated analog of nicotine. While Imidacloprid is safer than many insecticides, it is NOT a non-toxic chemical, so handle it with caution and avoid any ingestion. Furthermore, there is a potential link between Imidacloprid and colony collapse disorder in honeybees, so restricting its use to the greenhouse is recommended. It can be applied topically as a spray (be sure to get the undersides of all leaves), but when it’s included in watering, the plants will absorb the chemical and prevent biting insects (like scale) from attacking. If you have a severely infected plant you may need to pull it out of its pot and soak it in a bath of Imidacloprid and water. You can use Imidacloprid in conjunction with a mild insecticidal soap for a more intensive treatment.

WARNING! Many products that include Imidacloprid also contain fertilizer and are intended for much hardier plants than orchids, so look for products where the only active ingredient is Imidacloprid as regular plant fertilizers will burn your orchids!

Careful indoor use is ok – avoid use in the yard.
Oil A good quality horticultural oil can be applied. Most orchids can handle only a lightweight, or fine horticultural oil. The oil works primarily in suffocating insects by blocking the spiracles through which they breathe. The oils can also disrupt the metablolism of insect eggs and adults. Many orchid resources recommend neem oil, probably because it is less toxic than the petrolium-based horticultural oils people otherwise use, but neem can be too heavy for more delicate orchids such as those with thinner leaves. Cattleyas can handle neem fine and the results should be positive.

WARNING! Never apply horticultural or neem oil when the temperature is high (nearing 100o) as this will damage the plants.

Safe indoors and very effective as a long-term treatment.
Predatory insects Depending on your growing environment, you may also opt to introduce a predator, such as ladybugs, into your growing space. This, of course, is the most natural approach but is difficult for those that grow in homes. Of course, if you are taking this natural approach, be sure that you haven’t just sprayed any chemicals that are toxic to your predator. You can find more info on preditors at an organic garden store or at some hydroponic shops. Would be difficult to use indoors

Reapply the Imidacloprid (when watering) and spray with oil on a weekly basis. Watch for recurrence of scale. If a plant is continually being a host for scale and there seems no way to make it happy, you may need to discard of the orchid in order to keep your collection safe.

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Westland Resolva Bug Killer Liquid

Product Information

Resolva Bug Killer is a fast acting chemical which can be used to control a wide range of pests on over 30 types of fruit, vegetables and flowers.

Westland Resolva Bug Killer: Key Details

  • Suitable for greenhouse or garden use
  • Effective for up to two weeks after spraying
  • Can be used to control whitefly, aphids, caterpillars and many other pests
  • Contains 0.75g/l lambda-cyhalothrin as a micro-emulsion

Pack Sizes

  • 250ml concentrated formula
  • 1 litre ready to use spray
Controls the following insects:

Aphids (greenfly and blackfly), beetles, bugs (lygus), blossom weevils, capsids, caterpillars, cutworms, cabbage stem weevil, clay-coloured weevil, carrot fly, leaf-curling midges, leaf beetles (including rosemary beetle and lily beetle), pea midge, pea moth, pea and bean weevil, pear sucker, sawflies, scale insects, thrips and whitefly. Resolva Bug Killer Concentrate also give a reduction in the numbers of mealybugs.

Suitable to use on the following plants and crops:

Chestnuts, Hazelnuts (inc Cobnut & filbert) & walnut.

Herbs (outdoors only).

Dwarf French Beans, Runner Beans & Navy Beans, Broad Beans, Peas, Celery, Fennel & Potatoes.

Ornamentals, Flowering & Herbaceous Shrubs, Potted Plants & Flowers.

Natural Mite and Pest Control Options for Your Orchids

Posted August 5th, 2014 by Garden & Greenhouse in November-December 2014, Orchid Articles, Pest Control Articles

Every orchid grower knows that there are many enemies of your precious plants including a variety of pests and mites. There are many chemical products available that promise to eradicate different types of mites and pests infesting the orchids, but like all chemicals these harsh products often end up harming the plant as well. That is why keen orchid cultivators prefer to look for natural and organic ways of getting rid of these problems.

Mites are the most common pests amongst cultured orchids. They thrive in greenhouses and other warm areas like homes which are the best environment for growing orchids. Due to this reason, if you suspect that there are mites plaguing your orchids, then the first thing to do is increase the level of humidity in your growing area. As soon as the humidity level is increased in the growing area, the mites have trouble separating the water from the nutrients and they have to look for food elsewhere.

Some other natural ways to control various pests includes the use of ordinary kitchen products. Common rubbing alcohol can be sprayed on 2-3 times a day to get rid of certain soft bodied mites such as aphids, thrips and mealy bugs. Another way to eliminate these types of bugs is to spray a blend of garlic and hot pepper on the plants. You can make a concentrate by blending together 2 bulbs of garlic and 2 hot peppers with water, which can be later added to a gallon of water and sprayed on the plants.

For hard shell bugs like scales and spider mites, you can spray the following mixture 2-3 times a day: mix 1 teaspoon of dishwashing liquid and 2 teaspoons of cooking oil and spray it onto the plant where the mites are present. The dishwashing soap breaks down the insects shell and the oil helps to suffocate the bug, leaving your plants mite free.

Finally neem oil is considered to be one of the most effective natural insect repellent and fungicide for a variety of pests. You can liberally spray it onto your orchids without worrying about damaging them while enjoying a pest-free orchid garden.

Another major problem you might face when growing orchids in a greenhouse are the “green ants”. It is usually a never ending battle as not only do they keep increasing, but also tend to offer a free-for-all invite for aphids. So here are a few organic ways to get rid of green ants from your greenhouse:

  • Sprinkle some baking soda around your plants as it is poisonous for ants and is sure to keep them away.
  • Mix equal portions of flour and baby powder and sprinkle it in circles around your plants. The ants are sure not to cross the white line.
  • Spray a mixture of half vinegar and half water on your plants and the strong acetic acid in the vinegar will kill ants.
  • Sprinkle some chili powder, cinnamon, black pepper, peppermint or coffee grounds around the greenhouse or the plants, as they all keep the ants away.
  • Instant rice or cream of wheat is also placed around the plants because when the ants eat it and then drink water, the grains increase in size causing the ants to die.
  • Last but not least, you can mix borax powder along with sugar and water and dip them in cotton balls and place them near anthills. The ants will eat the sweet mixture, but the borax powder will kill them.

Weeds are another problem you might encounter plaguing your greenhouse floor. It is not easy to get rid of this nuisance by having to pull out entire sections of weeds from the greenhouse floor. Many people recommend spraying the harsh chemical sprays available to kill weeds, but like all other chemical products, these can also be harmful to your carefully grown orchids.

That is why the best way to naturally eliminate this problem from your greenhouse is to spray full strength vinegar on the weeds on a daily basis. However, this method is only suitable for weeds on the greenhouse floor or surrounding areas and cannot be applied to those found in your plant pots.

Using all natural products and solutions not only ensures that there are no harmful chemicals affecting your preciously grown orchids but are also safe for the grower to be around.

Mary Ann Berdak is the publisher of OrchidCareZone.com an online destination for orchid growing tips and advice. For more information on orchid care download her free report, “The 5 Biggest Orchid Mistakes (and How to Avoid Them!), at OrchidSecretsRevealed.com.

Want more information? Read these articles:

How Fertilization and Pest Control Work Together with Orchids

Lights, Misting Bottles and Pest Control for Orchids… Up Close and Personal

Orchid Fertilization and Pest Control

Orchid Pests and Problems

Spider Mites Eating Your Plants?

Pest Controls for Orchids-Part 3

Editor’s Note: This is the fifth of a 10 part series of articles about orchids. These articles are written by Steven Frowine, who collaborated with National Gardening Association and Wiley & Sons to produce the highly popular book Orchids for Dummies. We hope you enjoy this series of articles!

Here are more insect controls. Refer back to earlier posts for pictures and descriptions of these creatures.

Thrips

Neem is quite an effective, low toxicity insecticide that is frequently used by organic gardeners. For more info on this material go to this link:

One supplier of Neem is below:

Neem http://pestcontrol.domyownpestcontrol.com/search?w=neem&view=grid

OR

Insecticidal Soap http://www.domyownpestcontrol.com/bonide-insecticidal-soap-rtu-p-1667.html

Some folks use dilute liquid dish washing detergent, but be careful. Some soaps are phytotoxic (burn the leaves).

OR

DO NOT use DORMANT OIL SPRAYS on your orchids. They are a much thicker oil than the superior or all season oils and will severely damage your orchids. They are intended to be used on dormant fruit trees and outdoor ornamental plants, not actively growing plants with leaves.

Talstar

If you have a particularly bad or persistently problem with these guys you might want to try Talstar.

Scale

Isopropyl alcohol

Use on cotton swab and wipe across the armored shell of this insect. Make sure that you penetrate or break the shell of this insect.

OR

Insecticidal Soap, Neem or Superior Horticultural Oils See above for more details and suppliers.
This is a difficult pest to eradicate. You will have to apply controls repeatedly to get rid of it. Before I spray, I usually try to rub off the armored shells of the scale with my fingers then wash the leaf with mild soapy water. Then I spray with my chosen control.

For particularly bad infestations I have sometimes had to resort to a stronger systemic material like Orthene (Acephate).

If you decide to use Orthene, try to purchase it in the form like the container pictured below. This material is mixed with water so will not be as harsh to the orchid leaves as an oil based is.

Spider Mites

I hate these tiny guys. It is amazing how fast they can reproduce, especially in hot, dry weather. They can do a lot of damage.

To prevent mite infestations keep your orchid properly watered and in a growing area that is not too hot.

First: Wash off with strong stream of warm soapy water.

Then spray with Insecticidal Soap and/or All Season Horticultural Oil

See above for supplier.

If the infestation has gotten way out of hand you may need to use a stronger material like Orthene (Acephate). This can also be combined with the All Season Oil to be even more effective. Even with this material you may have to spray every 7 to 10 days for a total of three applications to wipe these guys out.

Snails and Slugs

Old beer. The yeast in beer is a strong attractant to snails and slugs. Put out a shallow platter, about ½” deep, of beer and wait for these creatures to belly up to the bar at nightfall. The next day you will find them drowned in the brew.

Another control: Put out pieces of lettuce in the evening that will attract slugs and snails. This lettuce, with attached feeding slugs, can be removed and discarded in the morning.

Sluggo® If you use baits, be sure that they are harmless to pets. Sluggo® is safe.

It is iron phosphate, which is a material commonly used in fertilizers.

Mice

Snap Traps

Good old snap traps still do the job. Peanut butter is effective bait. I do not recommend using poison baits. They could harm your pets and the mice that die from this poison frequently end up in the walls of your house and the sickening smell takes weeks to dissipate.

Live Traps

If you can’t stomach the idea of killing these creatures, you can use live traps and release them into your neighbor’s yard. Just kidding. Unless, you really don’t like your neighbors.

Of course, a cat is also a possibility!

Cockroaches

Roach aerosol sprays can ONLY be used on the floor, NOT directly on plants. The oil carrier in these aerosols can severely damage your orchid’s leaves.

Orange Oil both repels and kills roaches. And it smells good!

Also, a light dusting of Boric Acid works and is safe and odorless.

Fungus Gnats and other insect buried in the orchid media.

For any pests that are in the potting media, like fungus gnats, a simple, safe and effective control is to drown the buggers by submerging the pot and media for an hour or so in water. Before dunking the pot in the water, wrap the top of it with a cloth to prevent the bark or other potting media from floating out of the container when submerged.

General Info Chemical Controls

Many of the chemical controls for insects and diseases can damage the plants to which they are applied if misused. To be on the safe side, always read the pesticide label to see if orchids are listed as a plant that this chemical should not be used upon. And when applying the pesticide, never use more than the dosage recommended. Apply it in the cool of the early morning and make sure that the potting media is damp. Pesticides can much more easily damage a moisture stressed orchid.
To find more technical information on orchid pests and their controls, I highly recommend the excellent booklet published by the American Orchid Society titled Orchid Pest and Diseases.

Some Pesticide Notes and Reminders

  1. Don’t spray household aerosol insect controls, such as those designed for killing ants, roaches, and wasps on your orchid plants. These are intended to be used to kill insects outdoors and in the kitchen, and contain petroleum distillates that if sprayed directly on your orchid plants, can cause serious plant tissue damage.

  2. All horticultural oils are not the same. Use the ones called “superior” oils; do not use dormant oils. The superior oils are much thinner and more refined and are meant to be used when the plants are actively growing.

  3. Respond quickly to signs of insect problems. Miniature plants have small leaf areas so can very quickly become infested and seriously damaged.

  4. Apply the chemical where the bugs are—usually under the leaves and on new growth.

  5. In most cases repeated sprays will be necessary to gain control of the pest—usually once every 7 to 10 days for a total of three to four sprayings. The reason for this is that many of the eggs of the insects are resistant to the sprays used so will hatch out after spraying.

  6. Always use the least poisonous solution. Read the label and it will tell you its relative toxicity. These are the signal words to look for on the label and are in order from the least to most toxic.

CAUTION

means the pesticide product is slightly toxic if eaten, absorbed through the skin, inhaled, or it causes slight eye or skin irritation.

WARNING

indicates the pesticide product is moderately toxic if eaten, absorbed through the skin, inhaled, or it causes moderate eye or skin irritation.

DANGER

means that the pesticide product is highly toxic by at least one route of exposure. It may be corrosive, causing irreversible damage to the skin or eyes. Alternatively, it may be highly toxic if eaten, absorbed through the skin, or inhaled. If this is the case, then the word “POISON” must also be included in red letters on the front panel of the product label.

You should not have to use any material more toxic than “Warning” and try first those that only have a “Caution” signal word.

For the next article we will switch gears and talk about Lady’s Slippers!

This useful reference, Orchids for Dummies, which has been popular for both beginner and experienced orchid lovers, is available on Amazon.com and in book stores around the country.

How To Keep Orchid Pests From Ruining Your Plant This Summer

Summertime is bug time, and there are plenty of orchid pests to deal with. But knowing how to keep orchid insects from ruining your plant is a critical part to keeping it healthy.

One of the toughest parts about orchid care is that the environment that is good for your orchid is also good for orchid pests. Typically, if you’re dealing with orchid insects, they were there when you bought the plant. If you have more than one orchid, crawlers can move from plant to plant. That’s why it’s important to look for common orchid pests and take steps to get rid of them right away.

The American Orchid Society has a long list of orchid pests that you could potentially be dealing with, but we are going to focus on a few of the most common orchid insects out there. The good news is, what works on one insect often works on others, so you can apply these methods across the board in most cases. So, let’s take a look at a few of the most common orchid pests and what you can do to keep them from ruining your plant.

Orchid Pests: Scale Insects

In the world of orchid pests, there is no easy cure for a scale bug infestation. There are 27 different identified species of scale, but the most common experienced by orchid owners in the United States is brown scale. It’s characterized by yellow or brown oval “shells” and this orchid insect will kill your plant if left untreated. They can appear anywhere on your orchid:

  • Leaves
  • Petals
  • Sepals
  • Petioles
  • Pseudobulbs

Sometimes you’ll even find them on rhizomes and roots. One possible way to remove them is by picking them off or gently scrubbing them loose from the leaves and stems.

Management methods least toxic to people, pets and plants are the most time-consuming. But there are some less meticulous options.


  • Rubbing alcohol: All it takes is some 70 percent Isopropyl alcohol found in stores. Mix a solution 50/50 water and alcohol. You can apply it with a cotton ball or a misting bottle to get rid of scale infestations, but you will need to repeat the process every one to two weeks. The key to control is persistence.
  • Insecticidal Soap: is a safe and effective alternative to conventional insecticides. You can use bleach-free dishwashing liquid. Just mix 1 ½ teaspoons per soap with a quart of water.
  • Oil Spray: Mix 2 tablespoons of cooking oil and 2 tablespoons of baby shampoo in 1 gallon of water. This can also be mixed with 1 cup of alcohol to help penetrate the orchid insect’s shell. Shake well before and during application. Spray every five to seven days as needed, covering both sides of the foliage. Wash the leaves individually with the soap/oil mixture and rinse well.
  • Repotting: Your orchid potting medium can harbor scale eggs and crawlers, so repotting your orchid is one way to minimize the chances the scale infestation will continue.

Orchid Pests: Mealybug

Mealybugs are a serious orchid pest. They’re probably the most difficult orchid insect to control after scale insects. You’ll find them on all parts of your plants including on the roots, on the pseudobulbs and on the underside of leaves.

But they really like to hide on roots and rhizomes in your potting media. Rubbing alcohol and repotting are also good for controlling these orchid pests. Seventy percent isopropyl rubbing alcohol is what you’ll need in this case, too. If you already have mealybugs, try spraying your alcohol solution directly on the mealybugs with a misting bottle or pump sprayer. You may also have to drip some alcohol into tight areas. If you’re trying to keep mealybugs from ever showing up in the first place; spray all of the things around your orchid, including window-sills, table tops and furniture.

Just be sure to get your orchid out of the way, first, then move it back when your growing area is dry. Some oils and soaps are also good for keeping orchid pests like mealybugs at bay. You can try:

  • Horticultural oil
  • Neem oil
  • Mineral oil
  • Insecticidal soaps

You’ll spray your oil or soap, like you would rubbing alcohol, after watering them down and possibly mixing them with a plant-safe detergent. Just be sure not to spray on very hot days, or if your plant is in direct sunlight because your orchid leaves may burn.

Orchid Pests: Aphid

Aphids are among the most common orchid pests. They’re slow-moving, soft-bodied insects and are related to scale. There are three places to look for aphids:

  • On new growth
  • At the base of flower buds
  • On the undersides of leaves

Aphids can be removed from plants with a jet of water, squashed with finger and thumb or sprayed with organic garlic and chili sprays.

Orchid Pest Prevention Tips

Whether you have an existing orchid insect problem, or have dealt with orchid pests in the past, you’re going to want to minimize the chance of them coming back. Here are some things to do to keep the insects from becoming resistant to your treatment tactics:

  1. Change methods and chemicals occasionally.
  2. Do not use the same chemical mix more than three to four times in a row. For example, if you used rubbing alcohol for previous treatments, switch to an oil or soap.
  3. Never use an insecticide not labeled for ornamental plants
  4. Do not use less than the minimum concentration of a mixture.

Caring for your orchid is a lot easier when you’re armed with good information. If you’re looking for more orchid care tips, you’ll want to take a look at our guide, “Your Complete Care Guide for Every Stage of Orchid Life.”

Inside you’ll find care tips and helpful photos for each stage of orchid life. With just a little TLC, you can keep the bugs away and keep your orchid thriving.

PESTICIDE RECIPE: The Best Bug-Killing Mix for Mites, Mealybugs, Aphids, and Thrips
(Works well for orchids & house plants)

I don’t use systemic pesticides – they are not available for consumer purchase in Canada (save the bees, right?) so it’s not an option. Also, I grow plants exclusively in my home…systemics are not something you want to be breathing – and if you smell it, you’re breathing it. If you still don’t care about systemics and just want to get rid of the bugs (even if that means killing the bees), then you have lots of options to choose from, but you wont find those here.

Kills Spider Mites, False/Red Mites, Mealybugs, Aphids, and Thrips

Ingredients for the Best Bug for Killing Pesticide

  • 1 Cup of Water
  • 1/2 tsp – Dr. Bronner’s Peppermint Soap – after hearing the value of this from a few sites and from Glen Decker from Piping Rock Orchids, I started using this and love it.
    • Substitution soap: 5 drops of Blue Dawn Dish Soap; not sure why the blue version is specifically called for, but it appears that everyone on the web says THAT is the one that works best (and it worked for me, so I’m not arguing it).
  • 25-40 drops of mineral oil – I use baby oil.
  • Optional: Some people use 1/2 ratio of isopropyl alcohol to 1/2 water. I don’t because it makes it hard to breath when spraying a lot of plants and from experience it doesn’t seem any more effective than just water alone.

Added Oomf / Additional Bug-Killing Power

More Oils! You can use a combination of these, or all of them. Your goal is around 25-50 drops total (mineral oil AND whatever substitutes) per cup of water.

  • Neem Oil (10-20 drops)
    Often available at healthfood stores in the “pills + skin section”; coldpressed is what you want and it’s a solid at room temp, so you’ll need to heat it up before adding it to your soap/water mix.
  • Cinnamon oil / extract (10-20 drops)
    Stinks—makes your whole house smell like cinnamon (which sounds nicer in theory than it does in practice)…but it does seem to work well.
  • Eucalyptus oil / extract (10-20 drops)

Directions for Applying this Home-Made Pesticide to Infested Plants

In a spray bottle create a mixture of the above ingredients. I ensure the first 20% is warm water, then I shake it mixing up all the oils, then I’ll add the rest of the cooler water to top-up the spray bottle. Shake it up, mix the soap and ingredients around before each use, then generously spray the plant. Get the tops of the leaves, the bottom of the leaves, and the stalk/stem. Also coat the mites, aphids, thrips, mealybugs or whatever bug you’re trying to kill. Soak the top and bottom sides of all the leaves (it’s okay if it gets into the substrate/soil). Let it sit for about 5–10 mins. Spray again liberally; wait another 5 mins then take them to the shower (or sink) and spray all the leaves with clean water; let the water run through the potting mix for a while too to rinse out any soap.

Tips for Mealybugs & Thrips (hard to kill bugs):

If you really want to get rid of pests on a plant, repot it the first time you do this application. Spray the leaves, the stem, AND the roots…nuke the plant with the spray. I have eradicated spidermites and false mites with a single application by doing this.

Tip for Spider mites (the kind that make webs):

Use a really fine atomizer spray bottle and just make a nice clouding mist around the plant from top to bottom. The webs will grab the droplets and the spidermites are hooped b/c they cant walk around without getting stuck in oil. I don’t even drench plants that have these, I just give it a good and even misting spray a couple days in the week, followed by a shower at the end of the week and the spider mites are gone for another year.

Tip for False/Red mites (the kind that don’t make webs):

These things are a pain and will be all over the plant including on the roots and in the pot. Make sure you fully drench the plant if you have false spider mites…for orchids like phals and jewel orchids, it’s a good idea to repot them and spray the roots. If you’re not going to repot…then run that mix through the potting media a couple times so that it kills any on the roots or in the media.

Caution: Test this home-made bug spray first

Before you go spraying ALL of your plants with this mix, you may want to test it on your plants. Also, know this: orchid buds and blooms do not do well with alcohol or soap on them. I lost a giant spike on my Phal. Malibu Madonna that had over 20 flowers on it when I sprayed—all of the flowers: DEAD.

Why does this non-toxic mite, mealybug, thrips and aphid killer work?

The soap reduces the surface tension of the water and allows the oil to mix. The soap also has that surface-tension changing property on the bug’s waxy outside layer…so insects that can normally repel, now can’t. The ratio of water to oil helps distribute/dilute the oil so you’re not coating your plant in a thick layer of oil. The diluted oil is enough to coat the insect and they suffocate. In the cases where a bug is able to avoid suffocation by the mineral oil, the inclusion of other oils like neem, cinnamon, or eucalyptus make the plant surface less ideal for the bug. Neem stops them from feeding so it’s the best. Cinnamon burns my mouth…so I assume it does the same to the bugs. And Eucalyptus is likely toxic to many bugs…so it just makes sense.

Anyways, the point is, this mix suffocates and drowns your bugs.

Natural Feed and Insect Treatment

We do not like to use pesticides in our greenhouses. This is a personal choice to preserve our planet. But we also feel that it is a better way to grow orchids. Our approach is to use natural insecticides that feed and inoculate the plant at the same time. Strong healthy plants will fight off diseases.

No one is spraying poisons on orchids in the wild but they survive just fine. I often say that our cultivated orchids grow in spite of us not because of us.

Our main defense is Worm Tea. More properly called Vermi-liquid, it is the liquid extract from a worm bed. Humans have been growing plants in a symbiotic relationship with worms for thousands of years. We know it is beneficial for plants.

Worms excrete liquid and manure that is very rich in microbes that the plants need. When we spray an Orchid or soak the plant in the Worm Tea, the microbes enter the roots and become symbiotic with the plant.

Orchids and all plants can not absorb the Nitrogen and Phosphorus in fertilizers. It is the microbes in the soil that break these ingredients of fertilizers into a form the plant can use. Garden beds and potted plants build up a colony of these microbes in the soil. Orchids, since they are bare root or loosely packed in bark, do not have as much ability to sustain a colony of microbes. Some potting mediums like Coco Husk are sterile to start. By spraying Worm Tea, we are adding these microbes into the plant.

The most noticeable sign is the soaking of Vanda in Worm Tea. The roots will stay moist looking for several days. On a whole, I believe it is retaining about 30% more moisture in the roots.

An added bonus is the natural insecticide properties of Worm Tea. Worm Tea contains a chemical called ceitainese. It is harmless to humans and pets. It has one major feature in that it dissolves ceitain. Sprayed on us it does nothing, but sprayed on an insect it kills them. The skeleton of an insect is on the outside and made up of ceitain. It will dissolve the skeleton of scale even killing the Asian scale the is invading Florida’s Sago Palms. It is effective against thripes, aphids, mealy bugs and most insects.

When spraying for thripes and mealy bugs whether with chemicals or Worm Tea, understand that they have a three day life cycle. You must spray 3-4 times in a ten day period to eliminate the eggs or they just reproduce. Mealy bugs also stack on top of each other protecting the bottom bugs from the spray and not getting a 100% kill. Repeated applications are necessary.

Our second line of defense is Companion brand, bacillus bacteria. We use it against the common orchid problems of black rot, Pythium fungi, shriveling leaves, Fusarium wilt, and root rot, Rhizoctonia fungi.

Bacillus is a soil fungicide. It works systemically through the roots of the plant. It will kill early stages of black rot on leaves as a contact fungicide, but it is necessary to treat the disease early. Its real value is in the sterilization of the potting medium and the inoculation of the plant against infection. It is recommended to treat the plants every 28 days. We treat every re-potted plant with a drench at the time of re-potting and sprayed every 14 days. (We spray more often since in a large greenhouse plants are sometimes missed).

When we spray we spray everything, plants, leaves, flower buds and open flowers. Worm tea will add moisture to the flowers extending their life a little.

To the Worm Tea-bacillus mixture we add a rooting hormone of gibberic acid, found in Essentials brand. All three mix together and can be sprayed at the same time. In a 4 gallon backpack sprayer we add 10 ounces of Worm Tea, 1 ounce of Companion and 2 ounces of Essential. This does an entire greenhouse of about 4000 orchids. A one quart or one gallon garden sprayer will work for most hobbyist. These dilutions are for maintenance. We double the concentration of Worm Tea if there is an active pest attack and double the Essentials when we to try to revive a badly damaged root system.

For a test result of Essentials

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