Plant Pest Detective: Identifying Common Plant Pests
When you’re in the garden picking homegrown produce and find telltale bite marks on your plants, chances are you’ve got insect pests. Knowing what you’re dealing with when it comes to insects allows you to choose just the right treatment for getting rid of those uninvited dinner guests.
Here’s everything you need to know about the most common troublemakers so you can sleuth to successfully pinpoint and treat your insect pest problem. Some of these pests affect either edible or ornamental crops, while others damage both.
Aphids. Several species of this sap-sucking, winged pest exist. You’ll find aphids in green, black, yellow or red. They attack edible and ornamental plants, causing growth to be stunted, leaves to curl and yellow, and a honeydew buildup that leads to black, sooty mold. Ants are attracted to the honeydew produced by aphids, so include them in your treatment plan. Bagworms. Recognized for the bags they produce that hang down from various species of trees, bagworms can defoliate trees if infestation is heavy.
Cabbage worms. Green, hairy cabbage worms have a velvety appearance and a row of light spots along their backs. They are voracious feeders that eat vegetable plant leaves, creating large, irregular holes, often along the midrib. When feeding on cabbage, these worms bore directly into the head. Their excrement consists of greenish-brown pellets. After two to three weeks of feeding, the larvae pupate and attach themselves to stems by a silk thread. The adult cabbage moth is easy to spot; it’s white, with one to four black spots on its wings. Cicadas. Loud pests that buzz, cicadas create many sacks that hang down from tree branches. Signs of infestation include splits in twigs where the insects have laid eggs.
Colorado potato beetles. Distinctive ½-inch-long yellow insects, Colorado potato beetles feature black brown and yellow stripes on their wing covers. They gobble up and skeletonize the foliage on plants in the nightshade family, including potatoes, eggplant, peppers and tomatoes. Female beetles lay clusters of bright yellow-orange eggs on the undersides of the leaves. Slug-like, hump-backed larvae hatch from these eggs and molt several times during feeding, growing fatter each time. Corn earworms. Ravenous worms with a propensity to feed on the tip area of corn, corn earworms also attack tomatoes, fruit and bean pods. They leave extensive brown excrement around their feeding areas. Young worms are green with black heads and hairs, while mature worms are 1 ½ inches long and can be brown, pale green or light pink in color with many thorny microspines. The yellow adult moths lay small, white eggs on foliage and in the corn silk.
Cucumber beetles. Eye-catching cucumber beetles are yellow with black stripes or spots. The larvae are white and thin. As adults, these pests damage plants by feeding on leaves, soft fruit, shoots and blossoms. The larvae feed on roots, which causes plants to become susceptible to wind damage. Common targets of these beetles are cucumber, cantaloupe, watermelon, pumpkin, winter and summer squash, and gourds.
Flea beetles. Named appropriately, flea beetles are tiny green or black beetles that jump. They attack a wide range of plants, including fruits, vegetables and ornamentals. Adult flea beetles create pinholes in leaves. Japanese beetles. Notorious for skeletonizing leaves of a wide variety of edible and ornamental plants, Japanese beetles are have iridescent copper wings and a green-metallic thorax and head. Underneath they have small amounts of white hair along the sides of their abdomens. The eggs are white or cream-colored and the slightly curved larvae are gray-white with brown heads. Lace bugs. These gray pests are so called because they have lacelike wing covers. Lace bugs create tiny, light-gray spots on the upper part of fruit and ornamental tree leaves that can become stippled. When feeding, they leave behind dark brown honeydew excrement.
Leafhoppers. Flying or jumping when disturbed, these small, thin, wedge-shaped insects come in shades of green, brown and yellow, depending on the species. Leafhoppers feed on a variety of edible and ornamental plants and cause leaves to lose color, brown and become stippled. They also leave behind black excrement.
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Mexican bean beetles. Copper in color, Mexican bean beetles have eight black spots on each wing cover. They skeletonize the leaves of beans (their preferred hosts), as well as black-eyed peas, soybeans, cowpeas, mung beans, alfalfa and clover. The larvae are light yellow with a spiny appearance; the eggs are also yellow and found in clusters on leaves.
Scale. Circular, armor-like insects, scale are found on the stems of plants and the underside of leaves, and they often look like a part of the plant. They suck plant sap, creating honeydew and attracting ants, which require management as well.
Spittlebugs. It’s easy to spot the damage created by spittlebugs. Brownish-gray insects able to hop and fly, they produce a telltale foamy substance that looks like spit. It covers leaves and congregates in the forks of stems. Spittlebugs like to attack herbs, pecans and strawberries.
Squash bugs. Somewhat flat in shape, squash bugs are dark brown or black and congregate at the base of plants or under dead foliage. They have piercing mouthparts that suck plant sap, causing yellow spots on leaves that will often later wilt, blacken, die and fall off. The eggs are long and yellow in color. Stink bugs. Sap-sucking stink bugs are brown, green, or mottled and shaped like a shield. They feed on a wide variety of edible plants, including various fruit trees and some ornamentals. Fruits become puckered, scarred and experience cavities as a result of the feeding. The eggs are light red to yellow-red and are found on the underside of leaves. Tent caterpillars. Attacking various trees and shrubs, tent caterpillars defoliate and stunt plant growth. The adults are hairy and dark brown with a yellow-spotted stripe along the spine. The insect creates tent-like egg casings that encircle twigs during the winter months.
Thrips. These small, slender insects are brown, black or yellow and have fringed wings. Thrips damage fruit trees and ornamental plants. They suck on plants, which results in silvering and mottling of the surface of the leaves. They also leave behind black, shiny flecks of excrement.
Tomato hornworms. Known for quickly devouring the foliage of vegetable crops, particularly tomatoes, peppers, potatoes and eggplant, tomato hornworms can measure up to 4 inches long and feature posterior horns. The adults are large moths that appear at dusk. You can detect hornworms in the garden by the large amount of black excrement they leave on the ground near plants. Fortunately, all of these pests can be quickly and efficiently eliminated with GardenTech’s Sevin®- 5 Ready-To-Use 5% Dust. Simply coat affected leaf surfaces of vegetables, fruit, flowers and ornamental shrubs with a fine dusting, and say goodbye to trouble. Always make sure to follow package label directions carefully.
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