484 SYNOPTIC COLLECTION. 



mouth parts, as in most insects, but the antennae differ 

 from those of other orders in being elbowed and bent 

 upon the face. The mouth parts offer one of the best 

 illustrations of specialization by addition. Not only are 

 these strong, chitinous mandibles (PI. 1241, fig. i, md) 

 adapted for biting, cutting, kneading wax, crushing, and 

 chewing, but the two pairs of united maxillae (fig. i, mx', 

 mx") are fitted for piercing, sucking, and lapping. The 

 ligula (fig. i, mx", I) of the second pair of maxillae is the 

 part usually described as the proboscis and its length 

 varies in different species of bees in accordance with the 

 varying length of the corollas of flowers frequented by 

 these insects. 



The legs are long, hairy organs, and the tibia of the 

 third pair in the worker bee is provided with little cavities 

 or baskets for holding pollen. Thus it is seen that the 

 function of walking is combined with that of carrying 

 food. 



The tarsus or foot, a part of which is represented in 

 fig. 2, side view, illustrates the correlation of structure 

 and habit. By means of the hooks the bee walks on the 

 edges of its comb, and hangs from other bees, while the 

 soft cushion or pulvillus seen at the end secretes a sticky 

 substance which enables the insect to walk on the polished 

 surfaces of leaves and glass. 



The wings of the second pair are reduced in size like 

 the metathorax, which bears them. They are membra- 

 nous hence the name of Hymenoptera, meaning mem- 

 brane and wing and have few veins. The two pairs 

 (PL 1242, figs, i, 2) are fastened together by hooks. A 

 portion of the posterior edge of the fore wing turns under 

 in a plait (fig. i ; fig. 3, the plait enlarged) and a part of 

 the anterior edge of the hind wing is provided with hooks 

 (fig. 2 ; fig. 4, hooks enlarged) ; the two hook together as 

 seen in fig. 5. This specialized condition enables the 

 two wings to strike the air as one organ and long sus- 

 tained flight to become possible. 



