Family: Tachinidae
Subfamily: Phasiinae
Length: typically 5 to 7 mm
Flies in the genus Gymnosoma lay their eggs in Hemipteran hosts (True Bugs), on both nymphs and adults. Eggs are large and disk-shaped, and are attached to the host insect’s integument. When development of the embryo is completed, the hatchling burrows into the host.
D.M. Wood, in his treatment of the Tachinidae in McAlpine (1987), noted that all genera in the subfamily Phasiinae save one, lay unincubated eggs on Hemiptera. He added, "This is virtually the sole justification of the taxon." Morphologically the Phasiinae genera are quite different from each other. (By "unincubated" eggs, Wood was drawing a distinction with other Tachinids where the eggs undergo development within the female fly's body.)
Gymnosoma flies lack bristles at the apex of the scutellum, in contrast to the closely related genus Gymnocyltia, where there is a pair of apical bristles that cross each other.
In most species of Gymnosoma the abdomen is reddish orange with black markings. On the abdomen the short hairs extend from a raised base giving the abdomen a rough, though shiny, appearance. The pedicel and first antennal segment are elongate.
Insects of West Virginia