Eretmocerus is a genus of parasitoid wasps; they parasitise immature whiteflies.
Female with 5-segmented antennae with scape, pedicel, two funicular segments and club (club undifferentiated, often large and oar-shaped); male with 3-segmented antennae composed of scape, pedicel and club (club undifferentiated, elongate and exceptionally large). Forewing with stigmal vein very short; all tarsi with four segments.
About 84 species have been described.
Species with known whitefly hosts include: