Description and general biology
E. mundus is a minute wasp, 1 mm long and yellow in color. Its antennae are as long as the body. Males are darker than females. The shape of the antennae differs between the sexes. The wasp attacks the nymphal stage of the whitefly, preferring the second and third instars. Once a suitable host is detected, the wasp lays a single egg under its venter, i. e. in between the host and the leaf substrate. The larva hatching from the egg drills a hole into the host's venter, penetrates inside and starts feeding on the host's internal organs. The parasitic larva completes its development and pupates within the host. The adult chews a round hole in the host's dorsal side, through which it emerges.

Three pupae of Eretmocerus mundus within the
pupal skin of the sweet potato whitefly.
Adult female of Eretmocerus mundus.
Actual size: 1 mm long.

During the parasitoid larva's early development the host turns turbid white, and its mycetoms (two symmetrical round-shaped yellow-green bodies) disintegrate and migrate to the margins of the whitefly's body. Later on, the parasitoid pupa is clearly visible through the host's cuticular skin. The shape of the emergence hole helps to distinguish between a pupal skin from which a whitefly has emerged (T-shaped) and a pupal skin from which the parasitic wasp has emerged (round hole).
 
An E. mundus female can lay dozens of eggs during its lifetime. Development time (egg - adult) is approximately 2 weeks at 28°C. Adult females live approximately one week during summer months, and up to 2 weeks at milder temperatures (20-25°C).