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an order of insects characterized by complete metamorphosis. The insects vary in length from 0.2 mm to 6 cm. The order Hymenoptera is divided into the suborders Symphyta (sawflies and horntails), Parasitica (ichneumon flies and gall wasps), and Aculeata (wasps, bees, and ants). Some zoologists adhere to a different classification system.
Most hymenopterans have two pairs of transparent membranous wings. The fore wings are the stronger pair and are the leading ones in flight. The hind wings, which have simplified venation, are linked to the fore wings by hooks and form a single plane with the fore wings in flight. Sometimes wings are absent, as, for example, in worker ants. The mouthparts of primitive hymenopterans are formed for chewing. Higher species have mouthparts fitted for chewing and sucking: the labium is converted into a proboscis, which, in some bees, is longer than the insect’s body. Females have an ovipositor. In wasps, bees, and ants the ovipositor is converted into a sting. In some ants the sting is reduced.
Male hymenopterans develop from unfertilized eggs (haploid eggs), and females develop from diploid eggs that are usually fertilized. The females of only a very few species develop by parthenogenesis. In Parasitica and some Aculeata, polyem-bryony is sometimes observed. The larvae of Symphyta have a well-developed cephalic capsule and three pairs of thoracic legs; in sawflies abdominal prolegs also develop. In Parasitica and Aculeata, the larvae have an underdeveloped cephalic capsule and are wormlike, limbless, and almost immobile. Only the young larvae of a few ichneumon flies marked by hypermetamor-phosis acquire the capacity for independent locomotion. The pupae are exarate; they are often in a cocoon.
Most adult hymenopterans are herbivorous; some are predators. The evolution of flowering plants is closely tied to the evolution of pollinating hymenopterans (bees, wasps). The larvae of Symphyta, gall wasps, and some ichneumon flies feed on plant substances and live on plants or in plant tissues, sometimes causing tissue proliferation (galls). The larvae of some Parasitica and some Aculeata develop as ectoparasites or endoparasites of insects. Complex forms of caring for the young are observed in many Aculeata. Female spider, digger, and other solitary wasps build nests and feed their larvae with killed or paralyzed insects and spiders; solitary bees and Vespidae wasps feed their young a mixture of pollen and nectar. The most complex instincts are observed in such social hymenopterans as ants, social wasps, and social bees.
The oldest hymenopterans are known from the Lower Trias-sic. There are about 90,000 extant species, distributed predominantly in the tropics. Approximately 10,000 species are found in the USSR. Parasitica and some Aculeata (ichneumon flies, sco-liids, tiphiids, and ants) feed on harmful insects; some species are used for biological pest control. Many hymenopterans play a major role in plant pollination. Some species of honey bees yield such valuable products as honey, wax, and propolis. Some hymenopterans, such as sawflies, horntails, and gall wasps, are agricultural and forest pests.
REFERENCESZhizn’ zhivotnykh, vol. 3. Moscow, 1969. Pages 422–84.
Malyshev, S. I. Pereponchatokrylye, ikh proiskhozhdenie i evoliutsiia. Moscow, 1959.
Rasnitsyn, A. P. Proiskhozhdenie i evoliutsiia nizshikh pereponchatokrylykh. Moscow, 1969.
Sweetman, H. Biologicheskii metod bor’by s vrednymi nasekomymi i sornymi rasteniiami. Moscow, 1964. (Translated from English.)
G. M. DLUSSKII