206 Psyche [October-December 



old logs or dead, standing tree-trunks and fills any chinks or 

 openings with vegetable detritus/ The colonies are small, 

 comprising, when fully developed, scarcely more than 50 workers 

 and a dozen males. The workers are rather circumspect and 

 cowardly and the males tend to fly out of the nest as soon as it is 

 opened. The latter, like the males of Leptogenys and the 

 Dorylines, are frequently taken at lights. On April 14, 1922 

 a nest of geometricum, situated under the loose bark of a large 

 knot at the base of a standing tree trunk, was investigated and 

 found to contain an average colony of workers with some eight 

 males, a number of young and full grown larvae and a few cocoons, 

 which, as the senior author has shown (1915b) for this and other 

 species of the genus, are dark brown or black. One of the males 

 was copulating with a worker and as the pair failed to separate 

 even after preservation in alcohol, we have been able to secure 

 the accompanying photograph and drawing (Figs. 3 & 4). The 

 fact that the wings of the male had been gnawed away at their 



Fig. 3. Fertile worker and male of Diacamma rugosum gcoiiuiricum in copula, from the 

 left side x5. 



iNearly all the nests contain a number of small cylindrical vegetable bodies, which 

 prove to be the joints of the flower panicle of a peculiar grass (Rottboellia).' These 

 joints, each of which contains a seed, are scattered by the plant, collected by 

 the ants and stored in their nests. It would seem, therefore, that D. geometricum is tcv 

 some extent vegetarian. 



