BEES, WASPS, ANTS, ETC. 



503 



Oeder XI. — HYMENOPTERA. 



The order Hymenoptera includes the bees, wasps, ants, ichneumon-flies, gall-flies, 

 saw-flies, and allied insects. Many of these are well known to every observer. They 

 are among the first of insects to attract attention, and it is only necessary to cite the 

 popular names given above to convey a general idea of the more important characters 

 of the order. In structure they occupy a high place in the class Insecta. By many 

 entomologists they are now placed as the highest of insects ; and if the development 

 of their instinctive powers alone is considered there can be no doubt that they are 

 entitled to this rank. The marvellous intelligence of bees, was2.>s, and ants has 

 attracted the attention of men of all times. 



The more important characters of the order may be briefly stated as follows : The 

 mouth-parts are formed both for biting and sucking. There are four wings, which are 

 membranous, and have comparatively few veins. The second pair of wings is always 

 smaller than the first. The abdomen in the females is armed with a multivalve saw, 

 ovipositor, or sting. The metamorphosis is complete ; that is, the adult insect does 

 not resemble the larva in form. 



In the Hymenoptera the head is freely movable, and usually bears, 'in addition to 

 the large lateral compound eyes, three ocelli, which are arranged in a triangle on the 

 vertex. In many cases the ocelli are wanting ; and a few members of the order are 

 blind. The blind species are mostly ants which live in dark places. It is said also 

 that certain Chalcis-flies are blind. The antennae are variable in form in the lower of 

 the two sub-orders (Terebrantia) into which this order is divided. The number of 

 segments varies from three in certain saw-flies {Sylotomd), to sixty in some of the 

 Ichneumonidae. The general form of the antennae may be long, thread-like, short and 

 clubbed, or even pectinated. In some species they are smooth, in others hairy. 

 Often those of the males are more developed than those of 

 the females. In the higher of the two sub-orders (Aculeata) 

 the antennae are usually filiform, or setaceous and simple, and 

 almost uniformly composed of thirteen joints in the males 

 and twelve in the females. 



The mouth-parts are very highly developed. With other 

 insects the mouth is fitted either for biting or for taking liquid 

 food only. But the members of this order can both bite and 

 suck. The labrum and mandibles are essentially the same as 

 with other biting insects. In many species the mandibles 

 are very powerful, enabling the insects to perform wonderful 

 feats, even to piercing long tunnels in solid wood. With 

 these insects the mandibles are used much more as tools 

 to aid in building and provisioning their nests than they 

 are as organs for chewing food. The maxillae and labium 

 vary greatly in form in the different families. In the more 

 typical members of the order these organs are greatly 

 elongated, and form a kind of sheath for the labium and 

 its appendages. In this case the labium and maxillae to- 

 gether constitute a complicated apparatus for the collection of liquid food. 



The most obvious characteristic of the wings is the membranous texture which 



Fig. 628. — Mouth parts of a 

 bee. 6, olypeus; c, labrum; /, 

 mandibleEi; A_, maxillary palpi; 

 i, maxillie; j, labial palpi; k, 

 ligula; ;, palpifer; m, para- 



