Debbie Jackson, age 14, of Concord, N.H., for her question:
ARE THERE MANY BENEFICIAL INSECTS?
Insects are often grouped as beneficial or harmful, but this grouping is somewhat artificial. All insects form part of the great web of life that includes man and all other living things. Insects feed on plants and animals, but they also are food for plants and animals. Insects thus help keep in balance the total number of plants and animals. Insects thus help keep in balance the total number of plants and animals on earth.
Basically speaking, however, most of the world's insects can be classified as being beneficial to man.
Less than one percent of the 800,000 species of insects are harmful. Of the many thousands of species in the United States, only a few hundred are serious pests.
Beneficial insects include bees, wasps, flies, butterflies, moths and others that pollinate plants. In the United States, the value of crops that require or benefit from pollination by insects totals about $5 billion a year.
Many fruits, including oranges, apples, plums, strawberries, blackberries, pears and grapes, depend on insect pollinators for the production of seeds. So do such vegetables and field crops as peas, onions, carrots, cabbages, clover, alfalfa and cotton. Insects also pollinate carnations, morning glories, orchids, magnolias and other beautiful flowers.
Insects are an important food sources for birds, fish, frogs, lizards, skunks and many other animals. Insects even serve as food for such plants as Venus flytraps, pitcher plants and sundews.
Many people also eat insects. In South Africa, some people roast termites and eat them by the handful, like popcorn. Many stores in the United States sell fried caterpillars and chocolate covered ants.
Insects provide us with products worth millions of dollars yearly. These products include honey and beeswax, made by bees; shellac, made by lac insects; and silk from silkworms.
Many insects help keep the landscape clean by feeding on animal wastes and dead animals, or the remains of dead plants. Insects that live in the ground enrich the soil with their waste products and dead bodies.
Many insects benefit man because they are predators or animals that eat other animals. They feed on harmful insects. One of the most famous of these predators is the ladybug, which eats several kinds of crop destroying insects.
Other helpful insects are the parasites that live in or on the bodies of harmful insects. For example, some wasps lay their eggs in caterpillars that damage tomato plants. As the young develop, they feed on the caterpillars and kill them.
Some insects, of course, are not beneficial to man. Every year, harmful insects destroy about 10 percent of the crops raised in the United States. The major pests include boll weevils, which damage cotton; Hessian flies, which attack wheat; corn ear worms and chinch bugs, which destroy corn and other crops; and Colorado beetles, which feed on potatoes.