HYMEXOPTERA. 591 



moveable- head with large facetted eyes which in the male are 

 almost in contact, and three ocelli (fig. 486). 



In the antennae a large basal joint (shaft) and eleven to twelve 

 shorter joints can usually be distinguished, or they are not crooked, 

 in which case they consist of a greater number of joints. 



The mouth parts are biting and licking ; the upper lip and man- 

 dibles are constructed as in beetles and Orthoptera; the maxillae 

 and labium, on the other hand, are elongated and adapted for licking, 

 and when at rest are frequently bent round. In bees the tongue 

 can be considerably elongated and assume the form of a proboscis ; 

 in this case the lobes of the jaws also become considerably extended, 

 and form a kind of sheath around the tongue. The maxillary palps 

 are usually six-jointed ; the labial palps on the other hand only 

 four- jointed, but the number of joints may be reduced. 



As in the Lepidoptera and Diptera, the prothorax is firmly con- 

 nected with the following thoracic segments, inasmuch as the 



ti 



FIG. 480. Apis mellifica. a, Queen, b, Worker, c, Drone. 



pronotum at least (excepting in the leaf- and wood-wasps) is 

 fused with the mesonotum, while the rudimentary prosternum 

 remains freely moveable. On the mesothorax two small moveable 

 scales (tegulce) are found over the base of the forewing, and 

 behind the scutellum the anterior part of the metanotum is 

 developed into the posterior shield (postscutettum). Both pairs of 

 wings are membranous, transparent, and traversed by but few 

 nervures ; the anterior are considerably larger than the posterior. 

 From the outer edge of the latter small hooks arise, which are 

 attached to the inferior edge of the anterior pair, thus bringing 

 about the connection between the two pairs of wings. Sometimes 

 the wings are absent in one of the two sexes, or in the workers 

 amongst many social Hymenoptera. The legs possess five-jointed, 

 usually broadened tarsuses with long first tarsal joint. The ab- 

 domen is rarely attached to the thorax by its whole breadth (sessile) ; 

 as a rule the first or the two first segments of the abdomen are 

 narrowed to a thin stalk, bringing about the connection with the 



