Regarding this species, Brown (1965) states:

T. pusillus appears to be a soil dweller in cultivated and pampas areas as well as in forest (Kempf, 1961). It also seems to exist at higher elevations (e.g., in a coffee plantation at Venecia, near Medellin, Colombia). Probably it is strongly subterranean in foraging and nesting habits.

In Costa Rica I have collected this species from the north slope of Volcan Barba at 800m, just west of Monteverde at 900m, Cerro Cacao in the Guanacaste Conservation Area, and Pittier Biological Station at 1670m in the Cordillera de Talamanca. The Cerro Cacao collection was from beneath a stone under the stunted forest of Cerro Pedregal. The other collections were from Winkler samples of sifted litter from the forest floor. The collection from near Monteverde contained workers and a dealate queen.