322 Proceedings of the Royal Society of Edinburgh. [Sess. 
From this table it will be seen that the numbers emerging increased 
up to May 24 and then gradually fell off again. The cocoons from 
which the parasites emerged were kept in a dark wooden cage. In one 
side of this cage two holes about three-quarters of an inch in diameter 
were bored, and into these two tightly fitting collecting-tubes were fitted 
with their open ends inside the box. The Braconids being positively 
phototropic, entered these tubes immediately on emerging, and were then 
removed and counted before being set free. The numbers of the sexes 
were practically equal— 47 per cent, males and 53 per cent, females. 
Among these and several others which emerged later no hyper-parasites 
were observed. 
During May and the first week of June, when the Bracons were liberated 
on Drumshoreland, that area was almost continually swept by a cold east 
wind. When released the parasites made no efforts to fly, but crawled over 
the soil and the little twigs and pine-needles covering it, while numbers of 
them hid in the bark of stumps. Some flew a few feet, but alighted again. 
On May 26 and 28 the weather was warm and sunny, but the Braconids 
were no more active than on dull days. 
June 7 marked the close of the introduction of parasites, and Drum- 
shoreland was not visited again till June 14. On that date I examined 
the whole area for adult Bracons, but I observed none. They were 
all set free in the centre of the chosen area, with the view that even if 
they spread in all directions they would still be in the neighbourhood of 
their host the Pine Weevil grub. 
Two stumps were examined on June 18, and on one of them two 
batches of fourth-stage Braconid larvae were found, and on another one 
batch of seventeen larvae just about to spin. 
On July 8 the area was visited and three stumps carefully examined. 
Larvae and pupae of Hylobius were found, but no Bracon. The month of 
July was very wet, and except for casual visits no systematic examination 
was begun until the 22nd. Unfortunately, very few cocoons were found, 
but Hylobius pupae occurred in large numbers. 
It had been intended to examine every stump in the area, but the wet 
weather and the large number of stumps which yielded no cocoons were 
the cause of a change of method. The centre of the area was thoroughly 
examined and the stumps along eight radii from it. This should have 
given a fair idea of the extent of the parasitism. Altogether only ten 
batches of cocoons were found. 
On August 9 three grubs were found to be attacked by second-stage 
Bracon larvae, and another by fourth-stage larvae of Bracon. The felled 
