474 Phylum Arthropoda 



Family passalidae 



PASSALUS CORNUTUS* 



THE social reactions of Passalus comutus are of particular interest 

 in that it is one of the few social Coleoptera. 



The life cycle of this particular beetle is normally passed within de- 

 caying wood where it is safely hidden from light and observation. One 

 of the difficulties encountered in rearing these insects was the lack of a 

 method whereby normal reactions could be carefully observed. It was 

 finally discovered that by using decaying sawdust of the right degree 

 as a medium for galleries, and feeding the proper kind of decaying 

 wood in amounts too small for the adults to burrow in and conceal them- 

 selves, the actions of both adults and larvae might be satisfactorily 

 observed. 



Enameled cake plates approximately 2 inches deep were used for 

 brood dishes. Pieces of window glass were used to cover the plates, 

 and pieces of cardboard were then placed on the glass to exclude the 

 light. Great care was necessary to prevent the accumulation of refuse 

 in the brood dishes as the adults showed a tendency to plaster over the 

 glass covers and thus prevent observation of their activities. It was 

 found that the greatest activity occurred at night, and that artificial 

 light did not interfere with their activities if it was not too intense. 

 By placing a binocular microscope on the window glass covering the 

 brood dish, and adjusting it to focus through the glass, one could get a 

 very interesting picture of the actions of any specimen. Great care was 

 necessary, however, in moving the microscope in order not to jar the 

 dish and thus disturb the individuals to be observed. 



For purposes of observation several pupa cases were opened and 

 glass tops inserted. These were immediately plastered over. An 

 artificial pupa case was finally devised out of wet blotting paper and 

 fitted with a removable glass cover. This might be placed on a binoc- 

 ular platform and the interior of the case subjected to magnification. 

 Larvae transferred to this type of case went through the pupal changes 

 without injury. 



Cannibalism is very prevalent and forms one of the greatest diffi- 

 culties in carrying out observations on any particular larvae. 



Although clumsy and awkward in many of its movements, Passalus 

 is readily adaptable to the laboratory when provided with the proper 

 food and humidity. 



M. E. D. 



* Abstracted from an article in Ann. Ent. Soc. Amer. 25:709, 1932, by Warren C. 

 Miller, Bedford High School, Bedford, Ohio. 



