Temnostethus gracilis lives on the bark of various deciduous trees, both those densely covered with lichens and mosses, and on those that are quite smooth, such as ( Fagus sylvatica ), common ash (Fraxinus excelsior ) or aspens (Populus tremula ). They are predatory on aphids, Psylloidea, Psocoptera and mites, but also on other small arthropods.
Péricart, J.; Golub, V. B. (1996). Aukema, Berend; Rieger, Christian (eds.). Catalogue of the Heteroptera of the Palaearctic Region, Vol. 2: Cimicomorpha I. The Netherlands Entomological Society. ISBN978-90-71912-15-3.