Hymenoptera
A large and most important order of insects, distinguished by the possession of four membranous naked wings, supported by a network of nervures, and of a mouth furnished with jaws for biting. They undergo a complete metamorphosis, their larvae being usually like maggots, without feet, but with a distinct head; their pupae are inclosed in a cocoon, and are helpless, but the limbs lie free from the body, not adherent to it, as in the Lepidoptera. The insects are seldom of large size, but they are very numerous, and of very varied habits. The more important groups to horticulturists are the following: 1. Sawflies, or Tenthredinidae. In these, the female has a saw to bore a secure place for depositing the eggs in leaves or branches. The larvae feed on plants, and have six horny legs, and often several fleshy legs, or prolegs, behind, so that they often resemble larvae of moths. In the perfect insects, the abdomen and the thorax are closely joined, without any distinct stalk between them. Some of them make true galls on leaves and twigs of Willows. 2. In this class the females possess an ovipositor, and the abdomen is fixed to the thorax by a distinct stalk. The larvae are footless, and, except in one group, are parasitic in or on other insects: hence they are frequently beneficial. In this section are included the very abundant groups of the Ichneumons and the Chalcides, both parasitic, and the Gall-flies (Cynipidae), which are, in part, makers of true galls on Oaks, Roses, &c., and in part parasites. 3. The Sting-bearers (or Aculeate Hymenoptera). In these, the females usually possess a sting connected with a poison-gland, which they use as a weapon of defence. The antennae are simple, and are formed of thirteen joints in the males, and of twelve in the females. The larvae are footless, and are usually supplied with food brought by the perfect insects. The habits of the members of this section are extremely various. Some are solitary, and dig or build cells for the reception of their eggs, which they surround with food for the larvae--either honey or pollen, or small insects, stung, so as to remain helpless, though alive, till eaten by the larvae. Among these are the Solitary Wasps and Solitary Bees. Others live in societies (Honey Bees, Humble Bees, Wasps, and Ants), often very numerous, and with a very complex organisation. Often, in a community, there are perfect males, perfect females, and undeveloped females or workers, also called neuters. The workers do the work of the rest, and some may even be modified specially as soldiers, to fight in defence of the community. The Bees are of special importance to many plants, because of the great part they play in securing the fertilisation of flowers, and therby insuring the production of the seed. See Galls, Honey Bee, Humble Bee, Ichneumon Flies, and Sawflies.