Kim Taylor/Bruce Coleman Inc.
Wasps are highly important to ecosystems. Sawflies consume vegetation and so limit plant growth. Most other wasps are either parasitic or predaceous and therefore play a vital role in limiting the populations of thousands of other insect species. All wasps are eaten by other species, thereby providing many links in the food web. Many parasitic wasps have been cultured and used in the biological control of agricultural pests. Although a few of the stinging wasps are considered nuisances, they also provide benefits. Yellow jackets and paper wasps, for example, prey on caterpillars and other larvae that can destroy crops. Wasps feed on flower nectar and play a role in pollination.
All female stinging wasps can defend themselves and their nests by using their ovipositor to inject venom. Males do not have a stinger. No species will attack a human except in defense. If the colonies of some yellow-jacket and hornet species are disturbed, they may respond by releasing more than 100 defending wasps, each capable of delivering several stings. The nests of these species should be left alone or removed professionally if they are considered a nuisance. Wasp venom contains factors that release histamine, which dissolves red blood cells. Most people can survive many stings, responding with only temporary pain and swelling, but to hyperallergic individuals-about 1 percent of the population-a wasp sting can be fatal. If you are stung by a wasp, seek medical attention. If your pet is stung, find a nearby animal hospital.