1907.] Wheeler, Fxmgus-groxving Ants of North America. 689 



The nest of Trachymyrviex urichi is "excavated in clayey soils and 

 never anywhere else. It consists of one chamber at about the depth of 

 a foot and is never directly under the entrance hole, but always on one 

 side at right angles and about 9 inches away from it. It has a habit of carry- 

 ing the particles of earth which result from its mining operations a little 

 way from the entrance hole, say about a foot, and deposits them in a small 

 conical heap. . . .These ants also cultivate a fungus and if it is not Rozites 

 gongylophora it is very much like it. . . .Any roots of plants going through 

 the ants' chamber are not cut away, but are made to suspend their mushroom 

 gardens which are in their case regular hanging gardens .... They are noc- 

 turnal in habits and when di-sturbed sham death." They "seem to like 

 small fallen flowers and the fruit of various kinds of plants to be found in 

 gardens, but at the same time they do not despise rose plants, especially 

 the young and tender shoots. They are not at all energetic and are very 

 slow in their movements." 



The habits of Apterostigma urichi are described as follows: "Unlike 

 Atta this species does not excavate its nests but builds them in rotten trunks 

 of trees. . . .They are built in hanging position, i. e., the ants start working 

 from the top, but never let the nest touch the bottom of the cavity. Unless 

 the garden is quite recent and small it is always enclosed in a delicate white 

 covering, which at first sight looks like fine cobweb, with an exit hole at the 

 bottom. The nests therefore look like a more or less rounded ball and are 

 never larger than an apple. On breaking away this delicate covering a 

 small mushroom garden is found consisting of irregular cells in which the 

 ants, larvae and pupre are scattered." The fungus is similar to that desci'ibed 

 by Moeller for the Brazilian species of Apterostigma. "The gardens are 

 always found under rotten wood and the ants invariably use the excrementa 



of wood-boring insects as a medium for growing their fungus on The 



colonies of these ants are small, not numbering more than 20 or 30 dark 

 brown workers, all of about the same size, viz. 6-6^ mm. and with abnormally 

 long legs which measure 7-7^ mm. without the hip. They are of nocturnal 

 habits." The smaller A. mayri constructs similar gardens in dark cavities, 

 not only under rotten wood but also under large stones. It, too, collects 

 the excrement of wood-boring insects, but is also fond of fruits or even parts 

 of flowers. The mycelium has the kohlrabi aggregated into regular clusters 

 and according to Urich represents a more advanced condition than that of 

 A. urichi. The ants are nocturnal and sham death for many .seconds. 



Urich has also given us the only existing account of the habits of a 

 Sericomyrmex (S. opacu.s). "The nests of these ants are found commonly 

 about Port of Spain, in gardens, in the gra.ss as a rule, but sometimes in the 

 flower beds, and from their peculiar raised entrance can be readily recognized. 

 [Sept., 1907.] 4S 



