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As summer progresses, the number of insects found in our landscape increases. There are millions of types of insects in our world and more than 100,000 different ones active in the United States; however, less than 1 percent of these actually feed on plants in a harmful way.
Before you pull out the insecticide, take the time to identify the insects on your plants. You just may find out that they are beneficial insects. Beneficial insects are those that are helpful in some way, as predators or pollinators. A number of beneficial insects occur naturally in our gardens.
There are many more beneficial insect species than harmful ones. Many of these “good bugs” feed on the pests and keep them in check naturally. Three of the more common beneficial insects seen this time of year include the assassin bug, the lacewing and the lady beetle.
Nearly 3,000 species of assassin bugs exist; however, scientists suspect many more will be discovered. They vary in length from less than a quarter-inch to one and one-half inches. They come in many colors and shapes and most species have two pairs of wings. All assassin bugs, however, have a powerful, curved beak that they use to pierce and suck out the tissues of their prey. They prey on numerous harmful insects such as caterpillars, stinkbugs, aphids and beetles; however, they are generally predators and may feed on each other as well as other beneficial insects.
Since assassin bugs are themselves preyed upon by many enemies, they have developed a unique defense system, using their beak to squirt venom at their attacker as far as a foot away. Their saliva can cause irritation to human skin and induce a very painful “bite.” For this reason, both nymphs and adults should be handled with care.
Lacewings are small to medium-sized insects that are predaceous as both adults and larvae. They consume insect eggs and soft-bodied insects such as aphids and mealybugs. Because of the long life of the adults, voracious appetites, and high reproductive capacity, they are useful biological control agents.
Many people have seen the eggs of lacewings but didn’t realize it. The eggs are deposited at the end of a long hair-like stalk that is attached to plants or structures. This prevents the larvae from cannibalizing one another as they hatch. Looking like tiny “alligators,” lacewing larvae voraciously attack almost any prey they can grab, using pincer-like jaws. After injecting paralyzing venom, they suck the body fluids from their helpless victim.
Lady beetles are among the most beneficial insects. There are approximately 5,000 species worldwide with about 475 species occurring in North America. Not all adult lady beetles are the characteristic orange with black spots. Like many beetles, lady beetles have larvae that look nothing like the adult. Some people believe the larvae look like small orange and black alligators; however, there is great diversity in the lady beetle family.
Sometimes, gardeners mistake the lady beetle larvae for pests and spray chemical pesticides that kill them. This results in increased problems from real pests. Lady beetle larvae are relatively easy to find in your yard. Simply turn over an aphid infected leaf, and you will likely find them chomping away. The larvae are predators of aphids, mites, mealybugs, scales, whiteflies, leafhoppers, lacebugs, other pest beetles and caterpillars.
Send your gardening questions or comments to: Brunswick County Master Gardener Column, P.O. Box 109, Bolivia, NC 28422, or call 253-2610. Enclose a self-addressed stamped envelope if requesting information or a reply. Answers may be printed in this column.