Polyrhachis (Myrma) gagates F. Smith

Wheeler, W. M., 1922, The ants collected by the American Museum Congo Expedition., Bulletin of the American Museum of Natural History 45, pp. 39-269 : 262

Polyrhachis (Myrma) gagates F. Smith

Plate XXIII, Figures 1 and 2; Text Figure 70 Numerous workers and females from Zambi (Lang and Chapin). The interesting nest of this species is represented on Pl. XXIII, figs. 1 and 2, from two of several photographs taken by Mr. Lang and accompanied by the following note. "These ants nest in the ground. The entrances to the nest are surrounded by an irregularly circular mound of white, loose sand, which measures about 40 cm. in diameter, the sand being heaped up to a height of 13 to 15 cm. In the center of the mound then; is a tuft of grass (in one of the photos the stalks of the grasses have been cut off near the base, in order to show the entrances). In between the root-stocks of the tuft of grass, and leading into the nest there are numerous irregular entrances which are continued outside along the stalks, the sand being agglomerated with a sort of paper-like material so as to form a solid wall in strong contrast to the loose sand. The ground below the crater contains numerous galleries simply excavated in the sand. When the nest is disturbed, great numbers of ants run out and, when directly molested, discharge much formic acid. The chambers containing the larvae, etc., were immediately beneath the surface. No more ants were encountered at a depth of 20 cm. so that the nest is rather shallow. A few individuals were seen outside at 11 a. m., in the fairly strong sunlight. We saw a great many more of these nests, but no other as large as the one photographed. All the nests were found on a sandy island in the Congo River near Zambi, June 30, 1915, at a short distance from the shore. They were scattered over a plain which is evidently inundated during the rainy season, but which was dry at the time of our visit." Mr. Lang's description suggests that a certain amount of silk may have been employed by the ants in the confection of the paperlike entrances, as in the nests of some other earth- or wood-inhabiting; species of Myrma .