8 Common Garden Pests in North America

Though many insects and bugs live in our gardens, the majority of them aren't harmful to our plants. Some are even beneficial, because they pollinate flowers and/or eat pests. Toxic (both to insects and to us) pesticides kill indiscriminately, wiping out our allies along with the little villains in our gardens. Rather than spraying everything in sight, we should take a little time to determine what's actually living beneath all our greenery and then take appropriate action. Here's a list of some of the primary baddies to look out for.

1. Cabbage Loopers

These little (about 1½ inch long) green caterpillars are the larvae of mottled, grayish-brown moths. They have pairs of wavy white or yellow lines running down their backs, and one line running down each side. Three or four generations of them can hatch, pupate, and grow to maturity in a single year. Cabbage loopers chew huge holes in the leaves of many plants: cabbage (obviously), beets, celery, lettuce, peas, spinach, tomatoes, and many kinds of flowers can be ruined entirely.

2. Colorado Potato Beetles

You can sometimes find the bright yellow eggs of these beetles on the undersides of leaves. The adults are yellowish orange, with 10 black stripes running lengthwise down their wing covers. They are about 1/3 inch long. Each female can lay up to 1,000 eggs, producing up to three generations in a year. Potato, eggplant and tomato plants can endure light feeding at the hands of these pests, but large numbers of Colorado potato beetles will defoliate and eventually kill them.

3. European Corn Borers

These pests made headlines when the first genetically-altered corn plants were developed to combat them. Prominent in the Midwest and eastern North America, corn borers devour corn plants all over: on young leaves, on corn silks, and inside the husks. These larvae of yellowish-brown moths are about 1 inch long, gray or beige with brown heads.

4. Aphids

These insects are tiny - only a sixteenth of an inch to about three-eighths. They are pear-shaped and soft, with long antennae. Some have transparent wings longer than their bodies. Aphids can be pink, green, yellow, black, or gray. They reproduce explosively, and feed on most fruit and vegetable plants as well as flowers.

5. Japanese Beetles

These unwanted "imports" rapidly propagated and infested several states in New England. About ½ inch long, they have a metallic blue-green color, and wing covers that are bronze. They chew on leaves until there's naught left but skeletons. Some of their preferred victims are tomatoes, beans, corn, flowers (especially roses) and various fruits.

6. Spider Mites

You might need a magnifying glass to see these miniature spider pests, but yellow speckled areas on the leaves of your plants are a sure sign that they've been at work feeding. Adults and nymphs both attach themselves to the undersides of leaves and suck the juice from plants, eventually causing dropping leaves and stunted fruit.

7. Cutworms

Another type of moth larvae, cutworms are gray or dull brown with shiny heads. They generally feed from the ground, chewing through stems at the soil line until a plant falls - or eating it entirely, if it's a small seedling. New shoots, seedlings and transplants - of nearly any variety of plant - are thus particularly vulnerable to these pests. The average cutworm is about 1-2 inches long.

8. Cabbage Maggots

These white, wormlike fly larvae (about ¼ inch long) can cause serious injury to all kinds of plants in the cabbage family (cabbage, turnips, radishes, etc.). They burrow into the roots, either bringing outright death to plants or else causing the injured roots to become diseased and rot. Cabbage maggots don't propagate well during hot and dry summer weather, so they do the most significant damage earlier in the season when the weather is cooler.