BUTTERFLIES AND MOTHS IN AUTUMN 67 



from the boughs where they have fed in a numerous colony. 

 They strip the twigs almost bare by the time that they are 

 full-fed, when they are about three inches long. Unlike the 

 hawk moth caterpillars, they are thinly covered with short 

 hairs ; and they are easily identifiable by the narrow black 

 parallel lines which run nearly from end to end of their 

 bodies. Many of them are crushed underfoot, or by the 

 wheels of carts, as they cross the paths and 

 roads beneath these trees ; the survivors 

 pupate on the surface of the ground among 

 the herbage, and emerge at midsummer. 

 Then they are found clinging to the trunks 

 of trees, with their grey wings wrapped 

 round them so as to imitate a lichen-covered 

 stick or fragment of bark; and the buff 

 splashes at the end of the fore-wings 

 resemble the paler surface of broken wood. 

 Yet another method of protection is illus- 

 trated by the handsome caterpillars of the 

 pale tussock moth, which appear abundantly 

 at hop-picking time in September, and 

 are known in Kent and Surrey as hop- CATERPILLAR OF THE 



, , 1-1 i -j BUFF-TIP 



dogs. 1 hey are bright green, with vivid 

 black transverse bands, and five large tufts of yellow 

 hair, the last of which turns backwards like a dog's tail. 

 These conspicuous tufts serve as warnings to birds to 

 let their wearers alone. Cuckoos are the only birds 

 which habitually eat large hairy caterpillars ; for all other 

 species their bristles apparently make them an unwhole- 

 some diet. It must thus be a considerable advantage 

 to a caterpillar to be conspicuously protected in this way ; 

 and the hop-dog is one of the best examples of this device. 

 It spins a loose cocoon among leaves or other herbage, and 



