Sphaeropthalma pensyluanica reared from cocoons of the organ pipe mud dauber, Trypoxylon politum from Georgia over several years yielded only adult males. Possible explanations for this sex-biased emergence from this host are (1) obligatory heteronomous heterotrophy, in which the two sexes develop on entirely different hosts; (2) differential mortality in the immature stage, with female larvae dying during development; and (3) facultative size- dependent sex allocation, with female eggs laid only on hosts smaller than T. politum.
Matthews, Robert W.
"Unusual Sex Allocation in a Solitary Parasitoid Wasp, Sphaeropthalma Pensylvanica (Hymenoptera: Mutillidae),"
The Great Lakes Entomologist, vol 30
Available at: https://scholar.valpo.edu/tgle/vol30/iss1/5