1921] Wheeler: Some Social Beetles 97 



ionship, especially when the food supply is abundant. Thus O. 

 surinamensis is often found living with the rice weevil {Cal- 

 andra oi'yzse) , Cathartus advena with the Indian meal moth 

 (Plodia interpitnctella) and O. mevcator with a Tenebrionid 

 grain-beetle, Palorus subdepressus. Many of the species of 

 Lxmo'pliloeus constantly live in the burrows of Scolytid beetles 

 and feed on their dejecta. Owing to these peculiarities and espe- 

 cially to their very diverse and plastic feeding habits many of the 

 Silvanids and Lsemophloeids have become cosmopolitan house- 

 hold pests capable of doing considerable damage to many of the 

 staple stored foods of our own species. 



If with this general complex of behavioristic tendencies 

 exhibited by the European and North American Cucujids {sens, 

 lat.) we compare the activities of Coccidotrophus and Eunausi- 

 bins, we find that the latter while retaining many of the ancient 

 and primitive family traits nevertheless exhibit several of them 

 in a peculiar and highly specialized form. Thus the merely gre- 

 garious habits of the adults and larvfe of the northern and cos- 

 mopolitan Cucujids have become more definitely social in the 

 Tachigalia beetles, and their toleration of alien insects has 

 increased; the feeding of the ancient Cucujids on various vege- 

 table substances has become specialized to the point of concen- 

 tration on a particular tissue of a particular plant and both 

 adult beetles and larvae have become coccidophilous. The con- 

 struction of the cocoon, too, exhibits peculiarities not found in 

 any other Cucujids. Owing to the unusual interest of these 

 various specializations they may be discussed at greater length 

 under separate captions. 



1. Social Life Among the Coleoptera 



If we regard as truly social only those insects in which the 

 parent or parents live with their oflfspring, protect them and 

 either feed them directly or prepare materials for their susten- 

 ance, there seem to be only three groups of beetles that meet these 

 requirements, namely, the Platypodidae, the Scolytidse (Ipidae) 

 and the Passalidse. The Platypodidse and that portion of the 

 family Scolytidaj, comprising, according to Hagedorn (1910) the 

 tribes Corythalinje, Xyleborinse and Spongiocerinas, with some 

 400 described species, mostly tropical, are commonly known as 



