FAMILY LIFE 213 



Copris of especial interest to the student of insect biology 

 from the comparative point of view. It is believed that all 

 through the weeks during which the young are developing, 

 the parent keeps guard, fasting in the underground chamber 

 — her behaviour contrasting markedly with the " gluttony " 

 in which she indulged before the breeding season. 



Nearly related to the Scarabs and their allies are the 

 Passalidae — a group of large flattened beetles, black or brown 

 in colour, distributed through the tropics and warmer 

 regions of both hemispheres. These also display a family 

 life of quite remarkable interest, which has been elucidated 

 by F. Ohaus (i 899-1 900) and W. M. Wheeler (1923). 

 They live in galleries eaten out in decaying timber. The 

 parents guard the eggs after laying, and prepare food for 

 the larvae after hatching by breaking up the wood with their 

 jaws and partly digesting it. This is necessary because 

 the grub's jaws are too weak for direct attack on timber ; 

 the larvae *' are therefore compelled to follow along after 

 their tunnelling parents and pick up the prepared food." 

 In the darkness of their burrows, the Passalid beetles and 

 their grubs communicate with each other by audible signals, 

 the beetles stridulate by rubbing toothed surfaces below the 

 wings over similar surfaces on the abdomen, while the 

 grubs scrape the strong denticles carried by their very short, 

 unjointed " paw- like " hind legs over striated areas on the 

 sides of the thorax. The care of the parent Passalids is 

 said to be continued through the pupal stage of the offspring 

 until they assume the condition of mature beetles. 



The order of the Hymenoptera is well known as exhibit- 

 ing the most striking examples of parental care among 

 insects. In a previous chapter (V) some account was given, 

 in connection with a discussion on insect behaviour, of the 

 egg-laying, nest-making, and provisioning habits of various 

 digging wasps. Such creatures provide beforehand for the 

 needs of their offspring, but the mother does not survive 

 to see the hatching of the grubs and tend them as a fannily. 

 Many female Hymenoptera, however, have this relation- 

 ship with their young, and examples are afforded by the 



