Identifying Insect Pests

Find out how to deal with insect pests while leaving beneficial bugs alone.

Related To:

Cabbage Looper Caterpillar

Cabbage Looper Caterpillar

This pest is very destructive due to its voracious consumption of plants in the cabbage family.

Photo by: Image courtesy of R.J. Reynolds Tobacco Company Slide Set, R.J. Reynolds Tobacco Company, Bugwood.org

Image courtesy of R.J. Reynolds Tobacco Company Slide Set, R.J. Reynolds Tobacco Company, Bugwood.org

Tools and Materials

  • notebook
  • magnifying glass
  • camera
  • jar (for collecting samples)
  • insect field guide

Step 1: Examine the Plant

If you suspect an insect is causing problems, examine the plant. Check the leaves, top and bottom, looking for insects, caterpillars, and egg masses. As you touch the leaves, watch for scurrying or flying insects. Jot down notes, take a photo, or collect a sample so you can research the possible culprits using a field guide or gardening reference. Wait to spray until you've made a positive ID. Many insecticides will kill not only pests but also beneficial insects, including predatory insects that eat the pests and pollinators like honeybees.

If a plant is struggling, consider non-pest causes first. For example, if you see a wilted plant, check soil moisture. Gardeners sometimes mistake symptoms of nutritional deficiencies -- yellowing leaves, stunting, weak growth, poor production -- as indications of pests. If you see symptoms like these, consider testing your soil nutrients and pH levels.

Step 2: Identify the Type of Pest

Entomologists (insect specialists) often categorize insects by how they feed.

Chewing insects eat leaves. Symptoms include holes, ragged edges, and "skeletonizing" -- eating the tissue between leaf veins. Examples include weevils, caterpillars, flea beetles, and Japanese beetles. Look for the telltale frass (excrement) of the larger of these pests.

Sucking insects pierce a hole in plant tissue and suck out the fluids. Signs include stippling on foliage or silvery bronze leaves and discolored blooms. Examples include spider mites, aphids, thrips, and leafhoppers. These pests often leave behind moltings -- the outer skin they shed as they grow.

Other insects, such as wireworms, feed on roots. Cutworms feed at ground level, girdling young seedlings.

Tips

Once you've identified that you indeed do have a pest problem, determine whether control is really necessary. Is the damage located on the leaves of a plant you'll be harvesting in a week or two? Control measures may not be warranted. However, many pests multiply quickly so keep a close eye on pest populations.

Once you've identified the pest, research its life cycle and habits. Some pests, such as leaf miners that tunnel into plant tissue, will not be affected by sprays. Controls will be more effective if you catch the insect in the most vulnerable part of its life cycle.

Next Up

How to Get Rid of Carpenter Ants Before They Cause Harm

Learn what carpenter ants look like and how to manage an infestation in your home before the damage is done.

How to Get Rid of Crickets

Chirping crickets can drive you crazy if they get indoors, and they can damage your home. Large numbers of crickets can harm yards and gardens, too. We've got the tips you need to get rid of crickets.

How to Get Rid of Grubs

Grubs feed on the roots of your lawn and plants. Take control before these destructive pests get out of hand.

How to Get Rid of Spiders

Learn how to capture spiders indoors and manage potential infestations with these simple, natural tips.

Deter Deer in the Garden

Learn how to keep deer from destroying your landscape and backyard garden.

How to Get Rid of Flies

Find out simple steps for how to get rid of flies, indoors and out from the garden experts at HGTV.

How to Get Rid of Wasps

Identify and eliminate pesky wasp nests that affect your home and outdoor living areas.

How to Get Rid of Earwigs

Earwigs aren't pretty, and they can eat your plants and invade your home. Learn how to make earwigs bug off.

How to Get Rid of Spider Mites

Spider mites are among the most problematic plant pests, particularly for houseplants. Get tips on identifying damage from spider mites and learn how to get rid of them.

13 Ways to Get Rid of Slugs in the Garden

What’s slimy, has a voracious appetite and reproduces like mad? Slugs! Learn what you need to know to get rid of these eating machines.

Go Shopping

Get product recommendations from HGTV editors, plus can’t-miss sales and deals.

Follow Us Everywhere

Join the party! Don't miss HGTV in your favorite social media feeds.