Gardeners throughout North America have to be aware of the various insects that can show up unwanted in their gardens and cause damage to their crops. Many of these pests are the larval forms of moths, which attack specific plants in hopes of finding foods. The garden insects take their toll if left unchecked, eating stems, sucking on plants and chewing up the leaves of many kinds of vegetables.
Cutworms are a common garden insect that can cause great damage to plants. The cutworm, according to the University of Minnesota Extension, is the larval stage of many kinds of moth species that belong to the family called Noctuidae. These night-flying moths as mature flying adults do no harm to gardens, but the caterpillars will chew up plant stems both below and above ground. The cutworm will eat a wide assortment of garden plants, including peppers, tomatoes, beans, cabbage and carrots. While the cutworms have an array of appearances, almost all will roll into a fetal position that looks like the letter C when you touch them. Cutworms do their most damage to young developing garden plants.
While squash bugs typically feed on pumpkin and squash plants, this garden insect will attack other related plants, such as the cucumber. Squash bugs can be over half an inch long and they possess a flattened appearance, with a gray to brown color. The squash bug adult survives the winter hiding in the debris left from plants or in a sheltered area such as beneath a rock. The insects then come out in the warmth of spring to begin feeding on plants and to mate. Squash bugs feature a piercing mouth designed to suck the juices out of leaves, which can rob plants of needed water and nutrients, resulting in wilting.
The tomato hornworm avoids the midday heat by feeding upon the inner parts of a plant and staying out of the sunlight. When it migrates to the outer portion before nightfall or in the early morning, you can spot it, according to Colorado State University. The tomato hornworm can grow to 4 inches in length and they possess what resembles a horn on their rear ends. This type of caterpillar will chew on the foliage of such garden staples as peppers, tomatoes and potatoes. Its green color allows it to blend in to the plant and avoid detection from predators and gardeners alike. The tomato hornworm is large enough that you can pick it off the plant by hand and destroy it if you can find it.
The cabbage looper is a caterpillar that will feed upon vegetables such as cabbage and kale, chewing out holes in the leaves. The cabbage looper grows to be as long as 1 1/2 inches. The cabbage looper is green, with the older caterpillars having a telltale white line on their sides. The cabbage looper can decimate a plant by eating all the leaves, leaving only the veins of the leaf untouched. Some gardeners will plant their cabbage early in the growing season and then hope to harvest it before the cabbage loopers develop in enough numbers to damage it, notes the University of Rhode Island.