66 



leaves of the oak above mentioned, and that it has only within recent 

 years acquired a taste for the leaves of cultivated trees. 



At least one species of Tachina fly and a small four- winged ichneumon 

 fly belonging to the genus Apanteles prey upon these span worms; the 

 small, white, silken cocoon of the last-named parasite may occasionally 

 be found attached to the trunk of an infested tree, and near it the 

 shrunken body of the spanworm in which the larva of the parasite had 

 lived. Quite a large number of the spanworms are also destroyed by 

 birds, notably by the different kinds of blackbirds, which appear to be 

 particularly fond of them. 



Fig. 41. — Boarmia plumigeraria : a, male moth; b, female — twice natural size (original). 



Eepeated experiments demonstrated the fact that the most efficient 

 remedy for the destruction of these spanworms consists in spraying 

 the infested trees with Paris green and water, at the rate of 1 pound of 

 the poison to 200 gallons of water. This strength was found to be fatal 

 to the worms, while the foliage was not injured by it. About 10 or 12 

 pounds of soap should be dissolved in each 100 gallons of this solution, 

 in order to cause it to spread freely over the foliage. Almost any kind 

 of soap, either soft or hard, will answer this purpose. Care should be 

 exercised that the trees be sprayed when the worms are first hatched 

 out. At this time a very little of the poison will prove fatal to them, 

 whereas the nearly full-grown worms will consume a large number of 

 the poisoned leaves before succumbing to the effects of the poison. 



