Cryptochaetum iceryae (Williston)
Common name: Cottony-cushion scale killer.
Geographical distribution: This Australian endoparasitoid has been introduced and had become established in South America, Bermuda, California and Israel.
Host: Icerya purchasi, the cottony-cushion scale.
Morphology: A small, black, robust fly that, like other members of its family, lacks an arista on the antennae.
Economic importance: A specific natural enemy of the cottony-cushion scale, it locates and destroys even small, isolated host colonies.
Life cycle: A life cycle lasts about one month in summer, two months in winter. The parasitoid thus raises 6-8 annual generation, about twice as many as its host scales, which are parasitized from their 2nd-instar and on. Each female, which lives only for about 3-5 days, produces about 50 progeny, with a 1:1 sex ratio. Small scales are parasitized only by a single fly, but larger hosts, such as reproducing females, may suffice for the development of 10 parasitoids. The growth of parasitized scales is slowed and they turn yellow-grey, assuming a convex aspect as C. iceryae pupates within. The emerging flies leave exit holes in the body of the host. The parasitoid is susceptible to low humidities and high temperatures and thus more prevalent in cooler regions. It has several important attributes as a natural enemy. It increases twice as rapidly as the host and may be stored at 12°C for six weeks with minimal mortality. Due to the fact that C. iceryae parasitizes hosts only from their 2nd-stage instars, some scales escape its attack and serve as hosts for the its next generation.
Mendel, Z. and Blumberg, D. 1991. Colonization trials with Cryptochetum iceryae and Rodolia iceryae for improved biological control of Icerya purchasi in Israel. Biological Control 1: 68-74.
Quezada, J.R. and DeBach, P. 1973. Bioecological studies of the cottony cushion scale, Icerya purchasi Mask. and its natural enemies Rodolia cardinalis Mul. and Cryptochetum iceryae Will., in southern California. Hilgardia 41: 631-688.