1921] Wheeler: Some Social Beetles 103 



to the larvse. And although all the members of the colony, beetles 

 and larvae alike, seem to be very indifferent to one another, except 

 when they are competing for the honey-dew of the same coccid 

 or when larvse occupy cocoons in process of construction by other 

 larvEe, yet under normal conditions there are no signs of hostility 

 on the part of the beetles and larvse even when other individuals 

 are very annoying. Moreover, the use of the petiolar cavity as 

 a common domicile, with its kitchenmiddens and more or less 

 definite arrangement of the frass-ridges and wall about the 

 entrance, the droves of coccids and the definite orientation of the 

 eggs and cocoons, all shov/ a much more socialized condition than 

 anything that has been hitherto observed in other Cucujids. I 

 believe, therefore, that I am justified in regarding the two 

 TachigaUa Silvanids as representing a fourth group of social 

 beetles, of a more primitive type than any of the three families 

 above considered and differing in the absence of any definite 

 preparation of larval food by the parents. No such preparation 

 is necessary, in fact, owing to the peculiar conditions under which 

 the Coccidotrophus and Emiausibius live, since both the young 

 and the adults feed on the same substances and these are 

 furnished by the plant and the coccids, which in turn feed on the 

 same specialized parenchyma as the beetles. 



No doubt the toleration by the beetles and larvse of such 

 different insects as the coccids, the Scymnus larvse, the larval and 

 adult Diadiplosis, the Entomobrya, Aphiochaeta and probably 

 also of the adult Blepyrus, is due to the same causes as the tolera- 

 tion by so many ants and termites of numerous myrmecophiles 

 and termitophiles. Such guests, parasites and synoeketes can, of 

 course, manage to live only among insects which through long 

 association with individuals of their own species have come to 

 tolerate or even to seek the presence of insects belonging to alien, 

 or unrelated species. 



2. — The Development of the Feeding-Habits of 

 THE Social Silvanids. 



There would seem to be little doubt that the primitive food 

 of Coccidotrophus and Etmausibius is the nutritive parenchyma 

 of the TachigaUa petioles. But this is a very specialized diet 



