A key for distinguishing the three North American species of
Diachasma that have been reared from Tephritidae is provided by Wharton and Marsh (1978).
Diachasma muliebre is nearly identical to
Diachasma ferrugineum but the
sculpture of the
petiole differs slightly (Muesebeck 1956). The species from Western
USA (
muliebre) is apparently thelytokous whereas
ferrugineum is arrhenotokous, with normal production of males and females. The
ovipositor is distinctly longer than the
body in
Diachasma alloeum, and about equal in length to the
body in
ferrugineum and
muliebre. However, this character needs to be more critically examined because of potential allometry problems associated with hosts (and resulting parasitoids) that vary considerably in size. This and the other species of
Diachasma superficially resemble
Diachasmimorpha mellea, but
mellea and
muliebre can be readily distinguished by differences in the
clypeus, which is short (broadly exposing the
labrum) in
D. muliebre.