DESTRUCTIVE ANIMALS, BIRDS, INSECTS 119 



The following protective measures may be tried : 



1. Carry out frequent thinnings to remove dead and sickly 

 trees. 



2. Clear all felled timber from the forest by April. 



3. Periodically, from February to September, fell a tree or 

 two here and there to act as traps. Strip the bark off them 

 as soon as grubs are found at work, and burn the bark. 



4. Standing trees found to contain the grubs should be 

 felled and the bark stripped and burned. 



a Vi 



Fig. 4. Tortrix viridana, L. 

 a Moth. b Caterpillar suspended by a thread. 



Lepidoptera (Moths). 

 Oak-leaf roller moth (Tortrix viridana). 



This is a small moth, with its fore wings light green, and 

 hind wings light grey, which may be found in thousands in 

 almost any oak wood in June. The caterpillar is about half an 

 inch long, greenish-grey to dull green, with its head and anal 

 flap black, and with warts on its back. The caterpillars 

 appear in April and May, often in enormous numbers, and 

 spin threads, by which they let themselves up and down from 



