Start scouting for vegetable garden insect pests now

Squash bug eggs laid on the undersides of pumpkin leaf. Photo by Melody Hefner.

It is time to start scouting for insect pests in the vegetable garden. Here’s some information on a few common vegetable garden pests you should control now, before a serious infestation damages your garden.

Squash bugs attack plants in the cucurbit family: melons, squash, pumpkins and cucumbers. They damage plants with their sucking mouthparts, feeding on leaves and stems. The damage starts as speckling on leaves and stems, but a large infestation causes vines and leaves to wilt and die. Adult squash bugs are about ½- to ¾-inch long, brownish to grayish, and they blend in with the soil. Immature squash bugs look similar to adults, but smaller and often lighter-colored. They commonly hide on the undersides of leaves.

To prevent a large infestation, start scouting now for squash bug eggs. They are laid on the undersides of leaves, commonly in the V formed by the leaf veins. They are small, barrel-shaped and honey-to amber-colored. When you find them, scrape them into a cup of soapy water (dish soap works well). Do not scrape the eggs onto the ground, as they may still hatch. While you are scouting for eggs, grab adults or nymphs you find and drown them in the soapy water too.

Gardeners growing cole crops (cabbage, kale, broccoli, cauliflower) have likely seen ragged holes in their leaves. There are two small, green caterpillars that cause this damage. The first is imported cabbageworm, which overwinters as a pupa and emerges in early spring. Adults are white moths with one or two black spots on each wing.

The second green caterpillar on cole crops is a cabbage looper, which moves like an inchworm, looping its body up before moving forward. The adult is a brown to grayish moth. Cabbage looper caterpillars show up later in the growing season.

Both imported cabbageworms and cabbage loopers have multiple generations per season. Because these pests attack plants meant for our table, most gardeners do not want to apply insecticides. Hand-picking is a good option. Floating row covers can be used, especially if you are noticing adult moths flying around your crops. Row covers must be used early in the season to prevent adults from laying eggs on your crop; they won’t prevent eggs already laid from hatching and consuming your crop.

Most folks that grow tomatoes have encountered tomato hornworms. Adults are large, grayish sphinx moths, also called hummingbird moths. The larvae are green caterpillars that grow to 4-inches long. They have a horn-like tail that gives them their name. They also feed on peppers, potatoes and tomatillos. When young, they are very small and blend in with the color of tomato plants.

As tomato hornworms get larger, they consume more leaves and can do serious damage to your plants. As they feed, they leave behind black to dark brown droppings called frass. Start scouting now for frass on the leaves and in the branches of your tomato plants. If you notice frass, look above it on the plant to find the hornworm. Hand-pick and dispose of the caterpillar.

For additional information on these and other insect pests, go to and check out the insect and arachnid pests photo gallery.

Melody Hefner is the Urban IPM and Pesticide Safety Program Coordinator for the University of Nevada Cooperative Extension. Have a gardening question? Contact a master gardener at, or visit