]{. U. Dkakin 81 



of food, may have done something to account for the comparatively 

 small amount of danuige, which this year has been done to the oaks by 

 the caterpillars. Unless however T. viridana hibernates as a pupa, which 

 might serve as food for the birds, these could do little good in the winter 

 unless indeed they eat the eggs of T. viridana and C. hrwnata. 



Parasites. Oparahia has been mentioned as being parasitised by 

 a Tachinid fly. 



No case of parasitism on the winter moth larva was observed. 



Only a small percentage of leaf-roller caterpillars were parasitised. 



At the beginning of June 60 pupae were collected from the trees and 

 from these 43 moths hatched out. Twelve pupae died but were not 

 parasitised. The remaining five were parasitised, two by an Ichneumon 

 (Pimpla arctica), one by a Braconid {Meteorus laeviventris (Wesm.) and 

 two by Tachinid flies one of which was hatched out and identified as 

 Thrytocera (pilipennis Fin. ?). 



This gives a percentage of about eight parasitised caterpillars 

 The 60 pupae were not actually identified as T. viridana, but since all 

 the moths w^hich appeared were of this species there is little doubt that 

 the parasites appeared from this species also, but this requires con- 

 firmation. A caterpillar of T. viridana was also found with four bright 

 green hymenopterous larvae attached to the hinder part of the thorax. 



The caterpillar's condition was quite normal, it was apparently 

 about to pupate. 



The larvae which were about one-eighth of an inch long when full 

 grown, existed on the still living caterpillar for three days and then left 

 it and spun rough webs on the sides of the vessel in which they were kept. 

 They failed however to continue their development. 



Artificial Methods of Control. 



Two days, May 6th and 7th were spent spraying the trees of the Ham 

 Cross Plantation, it being hoped to cover the leaves with a stomach 

 poison whilst the caterpillars were still young. The spray used was 

 made from a paste of the following composition : 

 Lead chromate 20 or 50 % 

 Soft soap 10-25 % 



Gelatine •6-1-5 % 



Water 9 -4-23 '5 % 



I beheve this is almost the first time lead chromate has been used 

 in this country as a stomach poison for insect pests. The supply used 

 Ann. Biol, i 6 



