444 SYNOPTIC COLLECTION. 



teristics in the care they take of their young that are 

 utterly foreign to most Coleoptera and such as we shall 

 find farther on in the social Hymenoptera. 



The female of Platypus compositus deposits her eggs in 

 the galleries which are made by the beetles in the heart- 

 wood of trees. Here young (PI. 1128, fig. i) and old 

 (fig. 2) live together, and the galleries are always kept 

 clean and free from wood-dust. The larva is footless, 

 but its ridges and tubercles enable it to move rapidly 

 through the galleries. It feeds upon Ambrosia, a kind of 

 fungus (fig. 3) which is carefully propagated by the beetles 

 as their only food supply. The species of Ambrosia 

 eaten by Platypus has erect stems with swollen cells or 

 conidia at their ends. Hubbard says that "young larvae 

 nip off these tender tips as calves crop the heads of clover 

 but the older larvae and the adult beetles cut the whole 

 structure down to the base from which it soon springs up 

 afresh." The Ambrosia is started by the mother beetle 

 upon a carefully packed bed or layer of chips. In some 

 species it is grown only in certain brood chambers, and 

 in others "it is propagated in beds near the cradles of 

 the larvae." The excrement of the larvae is used to form 

 new beds for the propagation of the fungus. The older 

 larvae assist their parents in excavating the galleries ; in 

 this case not only do the adult beetles care for their young, 

 but the larvae "show evident regard for the eggs and 

 very tender young which are scattered at random through 

 the passages, and might easily be destroyed by them in 

 their movements. If thrown into a panic the young 

 larvae scurry away with an undulatory movement of their 

 bodies, but the older larvae will frequently stop at the 

 nearest intersecting passage " to let the little ones pass, 

 and will " show fight to cover their retreat." * 



The beetles that are most specialized by reduction are 

 the Curculionidae or weevils. The tiny strawberry weevil, 



1 Loc. tit., p. 15. 



