A laboratory study of the interaction of two parasites ofLymantria dispar [Lep.: Lymantriidae]: Blepharipa pratensis [Dipt.: Tachinidae] andBrachymeria intermedia [Hym.: Chalcididae]

In the laboratory, pupae ofLymantria dispar (L.) parasitized byBlepharipa pratensis (Meigen) were exposed to femaleBrachymeria intermedia (Nees) to determine whether the females would attack such pupae, and if they did, what was the fate ofB. pratensis. B. intermedia did attack parasitized pupae, andB. pratensis survived these attacks about 78% of the time. However, in those cases whereB. pratensis appears not to have survived, butB. intermedia did survive, the evidence suggests that the host pupae had not been parasitized byB. pratensis at the time of attack. Field observations also support the conclusion thatB. intermedia is not a significant mortality factor ofB. pratensis.