Not all insects are pests; in fact, a great many of them are beneficial to man. Entomologists recognize the good done by beneficial insects as well as the injury done by harmful ones. Predators, parasites, and pollinators are the most important beneficial insects.
Everyone recognizes the familiar ladybug, or ladybird beetle. Many species have an enormous appetite for aphids--one of our most common plant pests. Others prefer scale insects and mites and are very effective in reducing infestations.
Ladybug larvae are equally relentless predators. Their colorful, but ferocious appearance often causes unknowing gardeners to assume that they must be harmful. Nothing could be further from the truth.
The praying mantis is another widely-recognized insect predator. Nymphs and adults alike lie in wait for an unlucky insect which strays too close, then strike out to grab it with their modified front legs.
Ambush bugs use the same lie-in-wait tactic. Notice that their front legs are also enlarged and modified. The bright yellow colors of this species camouflage them in their favorite hideout--goldenrod flower.
The larvae of common lacewings are miniature monsters when viewed at close range. They are deadly enemies of small caterpillars, aphids, and other soft-bodied insects.
The lowly ground beetle, so common under logs and debris, is another friend of man. Both larvae and adults are predaceous and feed on a wide variety of insects.
Less common, but still important, robber flies are deadly enemies of grasshoppers, wasps, and other flies which they capture on the wing. Some of their prey are as large or larger than they are.
Tachinid flies are parasites of other insects. This fly has laid its small white eggs just above the legs of the caterpillar in front of it. Upon hatching, the fly maggots will burrow through their hosts skin and feed on its internal organs. The caterpillar will die just as the larvae emerge and complete their development.
In addition to these flies, many small wasps are important parasites of other insects. It is very difficult to measure how important these insects are, but there is no doubt that they are extremely valuable allies to us. Without their behind-the-scenes help, our pest problems would be infinitely worse.
The benefit of insects which pollinate flowers is somewhat easier to estimate since without them there would be no apples, pears, cherries, citrus fruit, nuts, berries, coffee, melons, cucumbers, squash, or many other common foods. Pollinating insects are estimated to be worth a least 8 billion dollars annually. Dozens of species of flower flies and wild bees inadvertently transfer pollen from one flower to another as they gather nectar to feed themselves and their young.
The best known pollinator and man s best friend among the insects in the honey bee. Besides the pollinating services it renders, this insect provides us with honey which we eat and beeswax which we use in making candles, polishes, inks, and cosmetics. It is hard to imagine what life would be like without the natural pest control, flower pollination, and products provided to us by these beneficial insects.
· 1 decade ago