METAZOA INSECTA. 483 



has undergone a chemical change in the honey bags 

 within the body of the bee. This helplessness of the 

 larva is in striking contrast to the independence of the 

 larvae of the Lepidoptera and of most generalized insects. 



The larva spins a thin cocoon for the protection of the 

 pupa (No. 1238). The appendages of the pupa are nearly 

 free, although each one is covered by a delicate skin. 

 The metamorphosis is rapid, twenty-four days being re- 

 quired for the male, twenty-one for the female, and only 

 fifteen or sixteen for the queen. 



The body of the adult bee (No. 1239; PI. 1240; fig. 

 i, <$ , fig. 2, 9 , fig. 3, 9 ) is shortened, compact, and hairy. 

 The three regions are clearly differentiated, the junction 

 between the head and thorax and the thorax and abdo- 

 men being a marked feature. 



The thorax is complex and its three segments are closely 

 consolidated on the dorsal side. The prothorax (PL 1241, 

 fig- J > ?>/) is reduced in size. Its side pieces are de- 

 tached from the dorsal portion causing the fore legs to 

 work in connection with the head. 



The mesothorax (PI. 1241, fig. i, ms) forms the greater 

 part of the thorax, while the metathorax (fig. i, mt) is 

 narrow. The unique character of the Hymenoptera is 

 the close union of the first abdominal segment (fig. i, ab'}, 

 usually called the median segment or propodeum, with 

 the metathorax. The tendency of this segment to press 

 forward is seen in the more generalized orders, like the 

 Orthoptera and Hemiptera, but nowhere is it carried to 

 such an extreme as in the Hymenoptera and Diptera. 



The narrow junction of the thorax with the abdomen is 

 effected by the short, slender peduncle (fig. i, ab"} which 

 is in reality the second abdominal segment, although usu- 

 ally described as the first. 



This articulation is doubtless produced by the habit of 

 stinging, and it is an extremely perfect mechanical con- 

 trivance. 



The appendages of the head are the antennae and 



