Only two species, Xystrologa grenadella (Walsingham) and X. nigrovitta (Walsingham), of the predominantly Neotropical genus Xystrologa are known to occur in the West Indies. Xystrologa antipathetica (Forbes), originally described from Puerto Rico but also reported from the United States (Florida), is considered a junior synonym of X. grenadella. The adults of both species and the larva and pupa of X. grenadella are described and illustrated. The larval habits of the genus are reported for the first time as a general detritovore, feeding on woody refuse, the bark of Ficus trees (in Florida, USA), fungi, and the roots of orchids, and pineapple (in Puerto Rico). The injury that larvae of X. grenadella can inflict upon cultivated orchids in Florida is summarized. The introduction of X. grenadella is reported for the first time in the Old World, as a pest of greenhouse plants in Germany.