Landscaping For Dummies
Book image
Explore Book Buy On Amazon

Whether you have container gardens or in-ground gardens, battling destructive insects is inevitable. When insect eggs hatch, they become larva, immature insects, which is often the most plant-destructive period of an insect’s life. Adult insects usually have wings and are at their most mobile life stage.

The following list includes the worst offenders of the insect world:

  • Aphids: These tiny (up to 1/8 inch), pear-shaped pests come in many colors, including black, green, and red. They pierce holes in plant tissue and suck the juices. Aphids can proliferate quickly on weakened plants and tend to congregate on the newest leaves and buds.

  • Bagworm: Adults lay eggs in bags in the fall. After hatching in late spring, bagworm caterpillars feed on the leaves and twigs of many trees and shrubs.

  • Bean leaf beetles: Adult beetles chew large holes in bean leaves and the larvae attack the roots.

  • Black Turfgrass Ataenius (Ataenius spretulus): These 1/4-inch-long black beetles lay eggs in turf grass in the spring. The eggs hatch into small white grubs, which feed on grass roots until midsummer.

  • Borers: Some beetle and moth larvae or grubs tunnel into the wood, canes, and stems of various trees and shrubs weakening the plant, and causing wilting and twig or cane death.

  • Cabbage loopers: The 1-inch-long gray adult moths lay eggs on cabbages and similar types of crops in late spring to early summer.

  • Chinch bug: Both the immature nymphs and the black-and-white, 1/6-inch-long winged adult bugs cause significant damage to lawns and grain crops by sucking the juice from grasses.

  • Colorado potato beetle: The yellow and black-striped adults emerge and lay orange eggs on the underside of potato-family leaves. The reddish grubs devour the plant leaves, mature, and lay a second generation of eggs.

  • Cucumber beetles: Striped and spotted cucumber beetle species cause significant damage by chewing large holes in leaves and vegetables, and eating their roots. They can also carry viral and bacterial wilt diseases, and spread them throughout your garden.

  • Cutworms and armyworms: The 1- to 2-inch-long cutworm caterpillars chew through the stems of young plants at night, kill them, and then spend the day curled in the soil nearby. Armyworms also feed at night, stripping the leaves from crops.

  • Gypsy moth: The adult moths lay masses of eggs that produce 2-inch-long caterpillars that are gray with brown hairs and distinctive red and blue spots. This pest spreads across the country as caterpillars and egg clusters hitchhike on cars and trucks.

  • Imported cabbage moth: The white moths have a distinctive black dot on each wing. The fuzzy green caterpillars feed on leaves and developing flower buds, leaving piles of green excrement.

  • Japanese beetles: Found mostly east of the Mississippi River, the fat, white, C-shaped, 3/4-inch-long larvae live in the soil, where they consume grass roots from early spring to early summer. The adults — 1/2-inch-long, metallic blue-green beetles with coppery backs — emerge from the soil in midsummer and attack plants with gusto, stripping leaves, buds, and flowers.

  • Lace bugs: These 1/8-inch-long insects suck the sap out of the underside of foliage, giving the leaves a whitish or yellow blotchy appearance. Look under the leaves for their brown, sticky droppings.

  • Leaf miners: The larvae of tiny sawflies, moths, beetles, and flies tunnel through the leaves of trees, shrubs, flowers, and vegetable plants, leaving discolored patches on the foliage.

  • Leafhoppers: These small, wedge-shaped adults jump from plant to plant sucking plant juices, distorting plant growth, and spreading plant diseases.

  • Root maggots: Small flies of several species lay eggs in the soil near host plants or on the base of the plant. When the maggots hatch, they burrow into the roots, killing or stunting the plant.

  • Snails and slugs: These pests proliferate in damp areas, hiding and breeding under rocks, mulch, and other garden debris.

  • Spruce budworm: These caterpillars cause significant damage to spruce and fir forests throughout North America.

  • Squash bugs: These brown, green, or gray, 1/2-inch-long bugs and their nymphs attack the leaves of squash and pumpkins. They become a problem when their population swells in late summer.

  • Tarnished plant bug: Very destructive plant bugs pierce plant tissues and suck the sap. The brownish, flattened oval bugs also spread plant diseases.

  • Thrips: These tiny, slender-bodied flying insects damage all soft parts of ornamental and vegetable plants, including leaves, flowers, and roots. Infested flowers and young fruits look distorted. Leaves have silvery or white discolored patches on them, sometimes speckled with black.

  • Whiteflies: Resembling small, white moths, these insects suck plant sap and spread plant diseases. Infested plants may release clouds of them when disturbed.

About This Article

This article is from the book:

About the book authors:

The National Gardening Association offers plant-based education in schools, communities, and backyards across the United States, through the award-winning websites and Teri Dunn Chace is a writer and editor with more than 35 titles in publication, and a long and distinguished career in horticulture and natural history. Phillip Giroux owns a landscape design firm. Bob Beckstrom is a home improvement expert and veteran author. Lance Walheim, former staff garden writer for Sunset magazine, is the nationally recognized author of more than 30 widely read garden books, including The Natural Rose Gardener.

This article can be found in the category: