Page:Encyclopædia Britannica, Ninth Edition, v. 24.djvu/417

Rh WASPS 391 WASPS. The order -Hymenoptera is divided into two sub-orders, the Terebrantia and the Aculeata. The latter is subdivided into several sub-sections, one of which, the Diploptera (Latreille), includes all the true wasps. The Diploptera are in their turn divided into three families- (1) the Vespidx, (2) the Ewnenidse,, and (3) the Masaridse, which together comprise some 1000 different species. They are characterized by their wings, which are present in both sexes and also in the neuters, being longitudinally folded when at rest. The antenna are usually elbowed, and contain twelve or thirteen joints ; in some cases they are clavate. A pair of notched faceted eyes are present, and three ocelli in the top of the head. The mouth-parts are arranged for sucking, but have not reached that degree of perfection found amongst the bees. Hence wasps cannot obtain the sugary secretion from deeply- seated nectaries, and their visits to flowers are confined to such as are shallow or widely opened ; they particularly frequent the Unnbelliferse. The maxillae are elongated, and compressed, the maxillary palp six-jointed. The labium bears a tongue which is glandular at the tip; the paraglossae are linear. The labial palp has three or four joints. The thorax is oval, and its sides prolonged backward to the base of the wings. The fore wing has two or three sub- marginal cells. The legs are not provided with any adaptations for collecting pollen. The abdomen is some times pedunculate, its anterior segment being drawn out into a long stalk, which connects it with the thorax. The females and the neuters are armed with a powerful sting. The usual colour of these insects is black, relieved to a greater or less degree by spots and patches of yellow or buff. The Diploptera may be subdivided into two groups in accordance with the habits of life of the insects comprising the section. One of the groups includes the family Vespidx, which is composed of social wasps, and includes the hornet ( Vespa crabro) and the common wasp ( V. -vulgaris). The other group contains two smaller families, the Eumenidse, and the Masaridae, the members of which are solitary in their mode of life. Family I. Vespidx. In addition to their social habits the members of this family are characterized by certain structural features. The anterior wings have three sub- marginal cells. The antennae have thirteen joints in the males and twelve in the females ; the claws of the tarsi are simple ; the anterior four tibiae have two spines at the tip ; the abdomen is but rarely pedunculated, and the posterior segments are often very contractile. The members of this family approximate very closely to bees in their social manner of life. The communities are composed of males, females, and neuters or workers. The latter are females in which the ovary remains undeveloped; they resemble the perfect female in external appearance, but are slightly smaller. Unlike the bees, the wasps com munity is annual, existing for one summer only. Most of the members die at the approach of autumn, but a few females which have been fertilized hibernate through the winter, sheltered under stones or in hollow trees. In the spring and with the returning warm weather the female regains her activity and emerges from her hiding-place. She then sets about finding a convenient place for building a nest and establishing a new colony. The common wasp (V. vulgaris) usually selects some burrow or hole in the ground, which, if too small, she may enlarge into a chamber suitable for her purpose. She then commences to build the nest. This is constructed of small fibres of old wood, which the wasp gnaws, and kneads, when mixed with the secretion from the salivary glands, into a sort of papier-mach6 pulp. Some of this is formed into a hanging pillar attached to the roof of tho cavity, and in the lower free end of this three shallow cup-like cells are hung. In each of these an egg is laid. The foundress of the society then continues to add cells to the comb, and as soon as the grubs appear from the first-laid eggs she has in addition to tend and feed them. The grubs are apodal, thicker in the middle than at either end ; the mandibles bear three teeth ; the maxillae and labium are represented by fleshy tubercles. The body, including the head, consists of fourteen segments, which bear lateral tubercles and spiracles. They have no anus. They are suspended with the head downwards in the cells, and require a good deal of attention, being fed by their mother upon insects which are well chewed before they are given to the larvae, or upon honey. At the same time the mother is enlarging and deepening the cells in which they live, building new cells, and lay ing more eggs, which are usually suspended in the same angle of each cell. The development within the egg takes eight days. After about a fortnight the grubs cease to feed, and, forming a silky cover to their cells, become pupae. This quiescent stage lasts about ten days, at the end of which period they emerge as the imago or perfect insect. The silky covering of the cell is round or convex outwards ; and to leave the cell the insect either pushes it out, when it opens like a box lid, or gnaws a round hole through it. As soon as the cell is vacated it is cleaned out and another egg deposited. In this way two or three larvae occupy successively the same cell during the summer. The first wasps that appear in a nest are neuters or workers, and these at once set to work to enlarge the comb, and feed the larvae, &c. The material which forms the substance of the nest is usually dried wood, worked by the mandibles of the wasp, with the addition of its salivary secretion, into a pulp, which can easily be moulded whilst moist ; it dries into a substance of a papery appearance, but possessing consider able tenacity. Sometimes paper itself, such as old cart ridge cases, is used. The combs are arranged horizontally ; each contains a single layer of cells opening downwards. The second comb is suspended from the first by a number of hanging pillars which are built from the point of union of three cells. The space between two combs is just sufficient to allow the wasps to cross each other. The combs are roughly circular in outline, and increase in size for the first four or five layers, after which they begin to decrease; the whole is covered by a roughly made coating of the same papery substance which composes the combs. This at first forms a cap-shaped protection, but as each comb is built it is continued down until finally it forms a roughly spherical covering for the whole, but not giving any support to the combs, which are independent of it. The covering is pierced by apertures for the passage of the wasps. The cells are hexagonal at their mouths, but above become more rounded in their cross section. During the first half of the summer only workers are produced, but, as fruit ripens and food becomes more abundant, fully developed females and males appear, the latter from parthenogenetically developed eggs of the later broods of workers. The males and females are larger than the workers, and require larger cells for their development ; these are usually kept apart from one another and from those of the workers. The males may be distinguished by their longer antenna?, by the more elongated outline of their body, and by the absence of a sting. In a favourable season, when the weather is warm and food plentiful, a nest may contain many thousands of cells full of wasps in various stages of development; and, as each cell is occupied two or three times in the course of a