Identifying garden pests: How to figure out who’s eating your plants

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Most gardeners face pest issues from time to time, and though we have a wonderful Guide to Vegetable Garden Pests here on our site, many gardeners often find themselves needing to be able to properly identify a pest before turning to such a guide for solutions to their problem. Garden pest ID is a task that can be very difficult, especially if the pest isn’t physically present on the plant when the damage is discovered. Today, we’re sharing an excerpt from the book Gardening Complete by the authors of Cool Springs Press (including several chapters by Savvy Gardening contributors Jessica Walliser and Tara Nolan!). We’re excited to be able to share it with you because the excerpt offers some very practical advice on identifying garden pests using methods you may not have considered before.

Excerpted from Gardening Complete by the authors of Cool Springs Press (February, 2018)

What is a Garden Pest?

In order for an insect to be deemed a pest, it has to cause a significant amount of economic or aesthetic damage to a plant. Yes, a lot of insects eat plants, but most of them do not cause significant damage. And, in most cases, the harm these insects cause is not life-threatening; it just makes the plant look not so hot for a short time. It’s surprisingly rare for a pest insect to outright kill its host plant; after all, it’s not in an insect’s best interest to eliminate its food source and the food source of future generations.

Gardens are complex ecosystems with many layers of organisms living in them. It’s important to remember that while some of these organisms are harmful to our plants, the vast majority of them are not.

Exactly what amount of economic or aesthetic damage is deemed “significant” depends on the tolerance of each particular gardener. Once you come to realize that most leaf-munching insects are not out to kill your plants, your tolerance for their damage should naturally go up. Obviously, if you’re a farmer who needs to grow near-perfect crops for your livelihood, your tolerance of pest damage that cuts into your bottom line will be far less than Joe Homeowner who’s just growing a garden to help beautify his outdoor living space.

Pest numbers also matter. One teeny tiny aphid is not a pest because the damage it causes is minimal, but hundreds of aphids can cause a far more significant amount of damage, and the gardener may need to step in with a management strategy. On the other hand, one tomato hornworm can nibble an entire tomato plant to the nub, so implementing a few management tactics is certainly called for, even when there’s just one hornworm present.

Aesthetic damage is often not harmful to the health of your plants; it just detracts from their appearance. In most cases, some amount of aesthetic damage should be tolerated by the gardener.

All this means is that deciding whether or not a particular pest is worth the time, money, and effort to control is best determined by careful consideration of your personal tolerance, the type of damage caused, and the number of pests present. Every gardener’s opinion on when it’s time to step in will vary, but I encourage you to not step in too soon, because not only are properly cared for plants very forgiving, but also, as you’ll come to learn later in the chapter, many pest issues are naturally managed by beneficial predatory insects.

Determining whether or not a pest is worth controlling, involves considering your personal tolerance, the extent of the damage, and the number of pests present on the plant.

Why You Need to Identify Pests in Your Garden

Another essential step in determining whether anti-pest action is required is to make sure you’re properly identifying garden pests and that you understand their life cycles and the extent of damage they can cause. For example, some pests have life cycles that only last a few weeks, while others only feed on plants for a short period of their lives, so taking action against a pest in one of these two groups isn’t worth the time and effort because the pest will be gone before they can cause much damage. On the opposite end of the spectrum are the insects that are capable of producing multiple, overlapping generations within a single growing season. Their populations can explode in short order, causing a great amount of damage in a relatively short period of time. The only way to know how much a pest’s life cycle influences the amount of damage it can potentially cause is by properly identifying garden pests and learning about them before you decide to take any action. There are several different ways to do this.

Methods of Identifying Garden Pests

1. Identify garden pests by physical description. This identification method considers the insect’s size, shape, coloration, leg count, wing count, and other physical attributes. It’s a useful method if you have access to a good insect ID book (see list below) or website where you can compare photos to the live insect in your garden.

Identifying insects, such as this blister beetle, by their physical traits is one way to determine who is nibbling on your plants. Use a good insect ID book or website to help with the sleuthing.

2. Identify garden pests by type of damage. Often the insect itself isn’t actually present on the plant; instead we just come across the damage. Identifying insects by the damage they cause is easier than it might seem. Many insects have very distinctive feeding patterns and the damage they leave behind is unmistakable. This method of identification often goes hand in hand with the next method, because when you find a particular type of damage on a particular host plant, it helps narrow down the possibilities even further.

3. Identify garden pests by host plant. In many instances, a leaf-munching insect pest only dines on a select few species or families of plants. Some insect pests are even so specialized that they can only consume one species of host plant (think asparagus beetles, holly leaf miners, and rose sawflies, to name just a few). Matching up the plant species with the insects that commonly feed on it is just another key to unlocking the identity of a pest.

Some pests have very distinctive damage that makes identifying them easy. Hibiscus sawfly larvae are responsible for this hole-filled leaf.

Sometimes just one of these three methods is all you’ll need for properly identifying garden pests. Other times, it may require using a combination of two or three of them.

Great Books for Identifying Garden Pests

To confirm the identity of the pest, you should then consult a good pest insect identification book or website. Here are some of my favorites for identifying garden pests.

Garden Insects of North America: The Ultimate Guide to Backyard Bugs by Dr. Whitney Cranshaw
Good Bug Bad Bug: Who’s Who, What They Do, and How to Manage Them Organically by Jessica Walliser
National Audubon Society Field Guide to Insects and Spiders: North America by the National Audubon Society
Kaufman Field Guide to Insects of North America by Eric R. Eaton and Kenn Kaufman

Identifying Non-Insect Garden Pests

For non-insect garden pests, you can use the same three methods you use for identifying garden pests that are insects. If you can’t see the animal eating your garden long enough to get a physical description (perhaps they dine at night?), look at how they feed on the plants and what plants they’re consuming. You can also look for footprints in and around the garden. Or, if you don’t see any footprints, sprinkle a coating of all-purpose flour around the nibbled plants and see whose footprints are in the dust the following morning.

Once you’ve properly identified the culprit and read up on its feeding habits and life cycle, it’s time to look into ways to prevent and control it. For that task, we recommend visiting our Guide to Garden Pests.

Related posts to help with pest management:
12 Organic weed control tips
Managing disease in the garden
Identifying and managing tomato plant diseases
Guide to vegetable garden pests
Deer-proof gardens: 4 sure-fire ways to keep deer out of your garden
Cabbage worm control methods

  • CSU/Denver County Cooperative Extension: Insects and Pests: The insect section includes non-pests, such as honeybees. Some of the fact sheets have insects in their various stages of development and offer cultural, natural, and chemical control methods. There is also a nice section on identifying and treating plant disease.
  • Cornell Cooperative Extension: Entomology Insect Diagnostic Lab Fact Sheets: If you’d like to dig deeper or see what the most current research says, this is your site. There’s a lot of great information here, but it’s not the place to go for a quick answer or a photo ID.
  • Ohio State University Extension: Insects and Pests: This is an all-inclusive site with fact sheets on structural pests and household insects as well as the critters in our gardens. It’s not big on pictures, and you’ll need to know what pest you’re looking for, but Ohio State has wonderfully thorough and easy-to-follow fact sheets.
  • Penn State: Home and Garden Pest Problem Solver: An all-inclusive site featuring lists of insect fact sheets. The site includes good photos, succinct information and advice, and links to other useful garden pest fact sheets.
  • Texas A&M AgriLife Extension: Insects in the City: Photos are grouped by beneficial, chewing, sucking, and soil insects. Just click on the photo and you’ll get enough information to know what’s happening to your veggies (and why) and what to do about it. You can also find the fact sheets listed by specific problems.

No gardener wants to see insects wreaking havoc on a bed full of ripening produce. Luckily, it’s possible to keep unwelcome visitors away. Since some pesticides can hurt the beneficial bugs that actually help your plants, try these easy control measures first before resorting to the strong stuff.

1. Aphids

Radu Bercan/

These tiny, pear-shaped critters have long antennae and two tubes projecting rearward from their abdomen. They usually hang out on most fruits and vegetables, flowers, ornamentals, and shade trees throughout North America. Aphids suck plant sap, causing foliage to distort and leaves to drop; honeydew excreted on leaves supports sooty mold growth; and feeding spreads viral diseases. To control these bugs:

  • Wash plants with strong spray of water
  • Encourage native predators and parasites such as aphid midges, lacewings, and lady beetles
  • When feasible, cover plants with floating row covers
  • Apply hot-pepper or garlic repellent sprays
  • For severe problems, apply horticultural oil, insecticidal soap, or neem oil

2. Cabbage Maggot

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These stick to cabbage-family crops, especially Chinese cabbages, and live throughout North America. The maggots tunnel in roots, killing plants directly or by creating entryways for disease organisms. To control these destructive creatures, try these methods:

  • Apply floating row covers
  • Set out transplants through slits in tar-paper squares
  • Avoid first generation by delaying planting
  • Apply parasitic nematodes around roots
  • Burn roots from harvested plants
  • Mound wood ashes or red pepper dust around stems

3. Caterpillars

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Caterpillars are soft, segmented larvae with distinct, harder head capsule with six legs in the front and fleshy false legs on rear segments. They can be found on many fruits and vegetables, ornamentals, and shade trees. Caterpillars chew on leaves or along margins; some tunnel into fruits. To deter them:

  • Encourage native predators and parasites
  • Hand-pick your harvest
  • Apply floating row covers

4. Cutworms

Sarah2/

Cutworms are fat, 1-inch-long, gray or black segmented larvae most active at night. They are found on most early vegetable and flower seedlings and transplants throughout North America. Cutworms chew through stems at ground level; they may completely devour small plants in May and June. For control:

  • Use cutworm collars on transplants
  • Delay planting
  • Hand-pick cutworms curled below soil surface

5. Colorado Potato Beetle

Sergiy Kuzmin/

Adults are yellow-orange beetles with ten black stripes on wing covers. They’re found on potatoes, tomatoes, cherry tomatoes, eggplant, and petunias throughout North America. These beetles defoliate plants, reducing yields or killing young plants. To control:

  • Apply floating row covers
  • Use deep straw mulches
  • Hand pick
  • Attract native parasites and predators
  • Spray with neem oil

6. Mexican Bean Beetle

Malcangi Valentina/

Adults are oval, yellow-brown, 1/4-inch beetles with 16 black spots on wing covers, while larvae are fat, dark yellow grubs with long, branched spines. They are found on cowpeas, lima beans, snap beans, soybeans in most states east of the Mississippi River as well as parts of Arizona, Colorado, Nebraska, Texas, and Utah.

Adults and larvae chew on leaves from beneath, leaving behind a lacy appearance. To control:

  • Apply floating row covers
  • Plant bush beans early
  • Hand pick
  • Plant soybean trap crop
  • Out out lures to draw spined soldier bugs (predators) to your yard
  • Spray with insecticidal soap or neem oil

7. Flea Beetle

InsectWorld/

Flea beetles are small, dark beetles that jump like fleas when disturbed. They hang out on most vegetable crops and are found throughout North America. Adults chew numerous small, round holes into leaves (most damaging to young plants), and larvae feed on plant roots. For control:

  • Apply floating row covers
  • Spray plants with garlic spray or kaolin clay

8. Tarnished Plant Bug

Steven Ellingson/

These are fast-moving, mottled, green or brown bugs that have forewings with black-tipped yellow triangles. They can be found on many flowers, fruits, and vegetables throughout North America. Adults and nymphs suck plant juices, causing leaf and fruit distortion, wilting, stunting, and tip dieback. To control these bugs:

  • Keep your garden weed-free in spring
  • Apply floating row covers
  • Encourage native predatory insects
  • Spray young nymphs with neem oil

9. Japanese Beetles

Kellis/

Adults are metallic blue-green, ½-inch beetles with bronze wing covers, while larvae are fat, white grubs with brown heads. They can be found on many vegetables, flowers, and small fruit in all states east of the Mississippi River. Adults skeletonize leaves, chew flowers, and may completely defoliate plants while larvae feed on lawn and garden plant roots. To control these insects:

  • Shake beetles from plants in early morning
  • Apply floating row covers
  • Set out baited traps upwind of your vegetable garden on two sides and at least 30 feet away
  • Spray beetles with insecticidal soap

10. Scales

SIMON SHIM/

Adult females look like hard or soft bumps on stems, leaves, or fruit; males are minute flying insects and larvae are tiny, soft, crawling insects with threadlike mouthparts. They can be found on many fruits, indoor plants, ornamental shrubs, and trees throughout North America. All stages suck plant sap, therefore weakening plants. Plants become yellow, drop leaves, and may die. Honeydew is also excreted onto foliage and fruit. For control:

  • Prune out infested plant parts
  • Encourage native predators
  • Scrub scales gently from twigs with soft brush and soapy water, and rinse well
  • Apply dormant or summer oil sprays
  • Spray with neem oil

Detection of plant leaf diseases using image segmentation and soft computing techniques

Agricultural productivity is something on which economy highly depends. This is the one of the reasons that disease detection in plants plays an important role in agriculture field, as having disease in plants are quite natural. If proper care is not taken in this area then it causes serious effects on plants and due to which respective product quality, quantity or productivity is affected. For instance a disease named little leaf disease is a hazardous disease found in pine trees in United States. Detection of plant disease through some automatic technique is beneficial as it reduces a large work of monitoring in big farms of crops, and at very early stage itself it detects the symptoms of diseases i.e. when they appear on plant leaves. This paper presents an algorithm for image segmentation technique which is used for automatic detection and classification of plant leaf diseases. It also covers survey on different diseases classification techniques that can be used for plant leaf disease detection. Image segmentation, which is an important aspect for disease detection in plant leaf disease, is done by using genetic algorithm.

Spring is the time of year when flowers bloom and eggs signify new life (or even a visit from the Easter Bunny!) However, not all eggs are ones that people may welcome in their homes, as some of them might be insect eggs.

Insect eggs in your home or business should be viewed as a warning sign to the types of pests that could be invading your home over the coming weeks and months. As your local pest control experts, we take pride in being able to correctly identify both pest species and their eggs.

If you think you have issues with insect eggs or other pest control problems, contact Rentokil for a survey of your property and to discuss pest treatment options.

Different Types of Insect Eggs

Flies in your home or business can be embarrassing. A fly-infested space gives off the impression that the place is dirty and unclean. The average lifespan of a fly is around 30 days, and they complete their full lifecycle within this time period. Wow, now that’s living fast!

Fly Egg Characteristics

  • Eggs are laid in large batches ranging from 120 – 1000 depending on the species of fly
  • Usually laid on a host specimen such as an animal carcass, rotting food or animal faeces
  • Hatch into a maggot like form before making the change into a fly
  • The eggs must remain moist or they will not hatch

Bed Bug Eggs

Blood thirsty and nocturnal, bed bugs can be silently laying batches of 10-50 eggs while you sleep. Correctly identifying bed bug eggs in your property is a good sign that you should be contacting a pest control professional as soon as possible. Bed bugs can spread quickly and are extremely difficult to completely eliminate without professional help.

Bed Bug Egg Characteristics

  • 1mm long
  • Pearly white colour
  • Are laid after an adult has fed
  • Can be found near where the adults hide during the day
  • Are attached to items of furniture or fittings in clusters

Cockroach Eggs

To say the least, there are many different types of cockroaches 3,000 known species in fact exist today that we know about. Likewise, the eggs that cockroaches lay are diverse and differ species-to-species. The two most common cockroach species in the UK are the German cockroach and the Oriental cockroach.

Image of a Cockroach egg case known as Ootheca

Cockroach Egg Characteristics

  • Female cockroaches produce egg cases known as ootheca
  • Ootheca contain many eggs and are enveloped by a protein substance that gradually hardens into a strong protective casing
  • Some cockroach species drop the egg case, while other species carry it until the eggs are ready to hatch
  • The number of eggs nested in the ootheca varies from species to species as well as the number of ootheca produced in a lifetime

Flea Eggs

Fleas: your pet’s worse nightmare. To avoid a nasty flea infestation in your property, be on the lookout for flea eggs. The usual suspects in flea infestations in the UK typically include the cat flea and dog flea. Much like cockroaches, flea eggs differ from species to species.

Flea Egg Characteristics

  • Main population of a flea infestation as 90% of a flea infestation is typically in the egg stage
  • On average a female flea lays more than 30 eggs per day
  • Hard to spot due to their size usually being around 0.5mm
  • White in color and sometimes transparent

Spider Eggs

While not technically an insect, spiders are also a common culprit when it comes to infesting buildings. Although often sources of fear and anxiety for humans, spiders for the most part are harmless to humans. Spiders often perform natural insect control for pests that could be considered more harmful. The way in which spiders lay eggs can vary throughout world depending on the species.

Spider Egg Characteristics

  • Eggs are laid into a silk woven sack
  • Where the egg sac is hidden depends on the breed of spider
  • The time of year in which spider eggs are laid depend on the species
  • The number of eggs laid at a time can vary from 2 to 1000 depending on the spider, this is also evident in the number of batches laid in a lifetime

Egg hunting with Rentokil

While it may be more fun to focus your egg-hunting activities on the chocolate kind, we encourage you to go on a pest egg hunt in your property. Perhaps you can stop a pest problem in your home before it starts. If you want to enlist the help of a pest expert, do not hesitate contacting Rentokil online to setup a pest inspection.

Connect With Us!

by Jessica Walliser June 14, 2012

I have spent a good amount of time this spring searching my yard for insects. I have a new book in the works with Timber Press about beneficial insects and am shooting many of the pictures myself. I’ve been learning a lot along the way and thought I might share some images of various insect eggs I have found in our yard. They are proof that the insect world is breathtakingly beautiful!

To see more images of the insects I find in my garden, you are welcome to friend me on Facebook at Jessica Walliser.

Green Stink Bug Eggs

Stink bugs have been a problem in my garden the past couple of years, but those are the brown marmorated stink bugs, native to Asia. The common green stink bug is native to the U.S.

Spined Soldier Bug Eggs

Spined soldier bugs are great to have in the garden. Aren’t their eggs amazing?

Leaf-footed Bug Eggs

The eggs of leaf-footed bugs are football-shaped and a bronze-gold color—stunning!

Monarch Butterfly Egg

Here on the leaf of common milkweed you’ll find the egg of a monarch butterfly.

Ladybug Eggs

If you find these eggs in your garden, consider yourself blessed. The beneficial ladybug helps control unwanted pests, like spider mites.

Green Lacewing Eggs
Green lacewings are a good garden insect. They lay their eggs on stalks to protect them from predators—and each other! Green lacewings turn to cannibalism if no other food is present soon after they hatch.

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Unless noted otherwise, photographs on this website are the property of the photographers and may not be reused without written permission from the photographers. To obtain permission, email the photographers here. High-resolution versions of the photographs are available.

Photos at the top of this website are (from left to right): potato beetle (Leptinotarsa decemlineata) — photo credit: Scott Bauer, U.S. Department of Agriculture; ebony jewelwing (Calopteryx maculata)— photo credit: U.S. Fish and Wildlife Service; sweat bee (Agapostemon splendens) — photo credit: Natalie Allen and Stephanie Kolski, U.S. Geological Survey; preying mantis, monarch butterfly (Danaus plexippus), hellgrammite (aka toe biter) larva and eyed click beetle (Alaus oculatus) — photo credit: Leslie Mertz, DailyGraceCards.com; Halloween pennant (Celithemis eponina) — photo credit: Kay Meng, U.S. Fish and Wildlife Service.

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