56 



INSECTS INJURIOUS TO THE APPLE. 



bands should be tied tightly in- the middle. Each caterpillar 

 is furnished with four pairs of fleshy prolegs, which are 

 fringed with small horny hooks, and on its trying to pass 

 over the cotton these hooks get so entangled in the fibres 

 that further progress becomes very difficult, and is seldom 

 persisted in. A shower of rain will pack the fibres of the 

 cotton somewhat, but where the string fastening it is tied 

 around the middle, the upper half washes down and makes 

 a sort of roof overhanging the lower portion, which in great 

 measure protects it from the weather. 



These larvae are seldom abun- 

 daut for many years in succession, 

 for in times of great plenty their 

 natural enemies multiply with 

 amazing rapidity. Several par- 

 asites destroy them. Two species 

 of Ichneumon flies prey on them, 

 also a two-winged Tachina fly, 

 closely resembling the Red-tailed 

 Tachina fly, Nemorsea leucanise (Kirkp.) (Fig. 46), which 

 attacks the army-worm, but this fly is without the red tail. 



Fig. 46. 



Fig. 48. 



A species of bug (Hemiptera) attacks the caterpillars just when 

 they are constructing their cocoons, and sucks them empty, 



