Hymenoptera
Insects with 2 pairs of membranous wings, often with the venation greatly reduced; the hind wings smaller than the fore pair and interlocked with the latter by means of hooklets. Mouthparts primarily adapted for biting and often for lapping or sucking als
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HYMENOPTERA (ANTS, BEES, WASPS, ICHNEUMON FLIES, SAWFLIES ETC.) Insects with 2 pairs of membranous wings, often with the venation greatly reduced; the hind wings smaller than the fore pair and interlocked with the latter by means of hooklets. Mouthparts primarily adapted for biting and often for lapping or sucking also. The abdomen usually basally constricted and its first segment fused with the metathorax; an ovipositor always present and modified for sawing, piercing or stinging. Metamorphosis complete; larva generally apodous with a more or less well-developed head, more rarely cruciform with locomotory appendages; tracheal system usually holopneustic or peripneustic throughout life, or at least in the final instar. Pupae adecticous, exarate (rarely obtect) and a cocoon generally present.
This order is one of enormous extent comprising more than 100 ooo described species and many thousands of forms still await discovery. If the Hymenoptera be judged by their behaviour, they must be regarded as including the highest members of their class. Structurally the majority of their species have attained an advanced degree of specialization which is only surpassed by the Diptera. In certain species of the order the individuals have acquired the habit of living together in great societies, as in the case of the ants, wasps of the family Vespidae and bees of the family Apidae. A large proportion of the females of these societies have undergone structural changes, in some cases slight, in others more pronounced, so that they constitute a separate caste or type of individual known as the worker whose power of reproduction is either in abeyance or usually limited to the laying of male-producing eggs. Their functions include those of nest-building, feeding and tending the brood and the defence of the colony. The normal reproduction of the species in the social Hymenoptera is either performed, as in certain wasps, by many of the female members of a colony or more usually by a single individual often of large size known as the queen. The sole O. W. Richards et al., Imms’ General Textbook of Entomology © O. W. Richards and R. G. Davies 1977
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GENERAL TEXTBOOK OF ENTOMOLOGY
function of the males is that of impregnating the females, an act which often comparatively few succeed in consummating. Indications of what, in the higher Hymenoptera, constitutes social behaviour are found among solitary wasps and bees (Wheeler, 1928). Most solitary bees and wasps practise 'mass provisioning' - i.e. they store their cells with sufficient food to satisfy their developing offspring and close them down before the eggs hatch. There are, however, species which feed their larvae from time to time ('progressive provisioning'), thus becoming acquainted with their offspring. Among tropical Vespidae of the tribes Ropalidiini and Polybiini many colonies are perennial and contain numerous fecundated females; their larvae are reared by progressive provisioning. Workers are often hardly differentiated and sometimes numerically weak. Such colonies, w
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