734 Mr. Gilbert J. Arrow on 



knowledge of insect economy. One of tlie beetles is 

 there stated to iiavc chirped so loudly when confined in 

 his room at night that he was unable to sleep until it was 

 put outside. Having had considerable success in rearing 

 the ]arva3 of other Lamellicornia, Dr. Ohaus tried to rear 

 those of Passalidas in the same way, many species being 

 very common in the neighbourhood of Petropolis; hut to 

 his surprise they invariably died in a few days. Deter- 

 mined to discover the reason of his failure, he devoted 

 himself for a time to the investigation of their natural 

 conditions of life, and soon observed that when a rotting 

 trunk contained tunnels inhabited by the larva?, a pair of 

 adult beetles was invariably to be found at the end of 

 each tunnel, each pair accompanied by from two to seven 

 young ones. Transferring the entire family to his breed- 

 ing-cage, ho found that they then fared perfectly well. 

 If individuals from different places were put together 

 they refused to settle down and soon died or killed each 

 other, but by keeping each family by itself he had no 

 difficulty in following out their history. The adults were 

 usually occupied in disintegrating the wood at the far end 

 of the burrow and chewing it into a soft condition ready 

 for the larv;^3, the condition of whose jaws seems to render 

 them incapable of procuring their own food. Even when 

 kept apart from their parents and the material prepared 

 by the latter supplied to tliera, they did not prosper, and 

 Dr. Ohaus considers it probable that a digestive secretion 

 is ndxed with it before it is given to them. The beetles 

 devote constant attention to their offspring from the time 

 they leave the Qg(^ until fidl maturity is reached, for even 

 after the young beetle has assumed its final shape the 

 jaws are for some time too soft for it to feed without 

 parental assistance. Both larval and adult Passalidse 

 stridulate loudly and constantly, and in these oiganized 

 communities it seems to be undernable that the vocal 

 powers serve the purpose of intercommunication. Dr. 

 Ohaus records an interesting episode which may be ([uoted 

 as a proof of this. 



Breaking up a log in search of larvae of another group 

 he disturbed a community of Passalidte consisting of the 

 parents and six larva;. Not wishing to keep these he put 

 them on the ground and went on with his search. Having 

 finished this he was preparing to leave when another log 

 near by attracted his attention, and he turned it over. 



