324 Proceedings of the Royal Society of Edinburgh. [Sess. 
Expt. No. 2. 
March 2. 1 male and 1 female placed in cage with bark containing 
Hylobius grub. 
„ 25. Hylobius grub with 10 well-grown larvae of Bracon feeding on it. 
April 1. Braconid larvae now yellowish. The Hylobius grub is sucked 
empty. 
„ 3. All Braconid larvae, except 3, spun up. 
„ 5. All Braconid larvae spun up. 
„ 6. One Braconid larva removed from its cocoon to see if it would 
spin again. 
„ 9. This larva shrivelled up. 
May 13. Cocoons still intact; they were examined, but only shrivelled 
larvae were found in them. 
Expt. No. 3. 
March 20. Male and female Bracons put in cage with bark containing a 
Hylobius grub. 
May 6. 14 Bracon cocoons and the head of the parasitised Hylobius grub. 
„ 24. The cocoons are empty, all the emerged Bracons being males. 
As will be observed on comparison with later experiments, this series 
was subjected to as little disturbance as was necessary, in order to avoid 
failure through tampering with the larvae. 
Unfortunately, the first two experiments failed and the third produced 
males only, but they showed that Bracon could be reared in the laboratory. 
The failure of the second experiment demonstrated the need for uniformly 
moist conditions. 
Series 2. 
These experiments were carried out with cocoons collected in April 1915. 
They were subject to more frequent and particular examination than those 
of the first series. 
Expt. No. 1. 
May 27. 1 male and 1 female Bracon placed in cage with bark containing 
a Hylobius grub. 
„ 28. Cage placed in the dark. 
„ 31. Eggs of Bracon on Hylobius grub. 
June 1. 8 Bracon larvae and 5 eggs on grub. 
„ 2. All eggs hatched. 
„ 3. Larvae in second stage. 
„ 4. Larvae in second stage 1'5 mm. long. Grub now quiescent. 
