206 
Psyche 
[Oct ober- Decern ber 
old logs or dead, standing tree-trunks and fills any chinks or 
openings with vegetable detritus. 1 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 larvse 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). Th e 
fact that the wings of the male had been gnawed away at their 
Fig. 3. Fertile worker and male of Diacamma rugosum geometricum in copula, from the 
left side x5. 
'Nearly 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 to 
some extent vegetarian. 
