While ovipositing eggs in flower buds, a female Fergusonina also passes parasitic nematodes from within her own body. The nematodes feed on the bud, caus ing galls to form. Inside the gall cavity, the newly hatched fly larvae feed on the sap oozing from the nematodes. Third instars feed directly on gall tissue. Before pupariation, fertilized fe male nematodes enter the hemocoel of female fergusoninid larvae and change into parasitic forms.
More species await description.