58 



Zoologica: N. Y. Zoological Society 



[III; 3 



FIG. 8. 

 pronotum of pupa of Eunausibius wheeleri showing lateral tubercles : 6, to /, pronota 

 of five pupse of Coccidotrophus socialis, showing vestigial lateral tubercles and 

 their variation. 



lations, or kitchen-middens in the pointed ends of the cavity. 

 When this crowded condition is reached, beetles begin to leave 

 the colony either singly or in pairs, seek and enter other petioles 

 of the same or other Tachigalias and thus establish new colonies. 



In order to study the stages of colony development just 

 described as well as those that supervene, I found it necessary to 

 split each petiole longitudinally and to place its two halves, with 

 their cavities turned outward in a slender vial or test-tube plug- 

 ged with cotton. The cotton could be pushed in till it held the 

 two halves firmly against the inner surface of the glass. Through 

 the latter the behavior of the beetles could then be studied with 

 the pocket-lens (magnifying 10-20 diameters) or the binocular 

 dissecting microscope. Splitting the petiole, of course, so greatly 

 disturbs the insects that many of them at once escape into the 

 tube. Moreover, a certain number are killed or injured by the 



