AbstractMetaphycus flavus(Howard) (Hymenoptera: Encyrtidae) is a facultatively gregarious endoparasitoid of soft scales (Hemiptera: Coccidae). When it develops in superparasitised hosts, the larvae often attack and consume brood mates six or more days post oviposition. Under our laboratory conditions (25±1°C and 14 hours of light followed by 18±1°C and ten hours of darkness in 50–70% R.H.),M. flavuseggs hatched three days after oviposition. Measurements of the mandibles and tentorium indicate there are four larval instars, andM. flavusreaches the fourth instar by day six post oviposition, and pupates on day eight. Thus, cannibalism amongM. flavuslarvae occurs during the fourth instar. During this instar,M. flavuslarvae separate from their attachment to the scale cuticle, to which they were tethered by a respiratory structure during the previous three larval instars. Once detached, they are free to move within the scale, which increases the probability of larval encounters and aggressive behaviours. Moreover, the mandibles of the fourth instar are better adapted for fighting than are those of the first three larval instars, since they are larger and more sclerotized. The cranium and mouthparts ofM. flavushave four different types of sensory organs, some of which are almost certainly olfactory, an unexpected function for a larva that presumably is surrounded by an aqueous medium where gustatory sensilla would seem to be more appropriate. The cranium also bears two pairs of what appear to be secretory pores.
The efficiency of Paecilomyce farinosus as biocontrol to larve stage on second ad sixith instar larve of Trogoderma granarium (Everts)
