96 INJURIOUS AND USEFUL INSECTS 



used in holding on. A pair of small cerci (tail-like pro- 

 jections) stand out backwards from the last segment. 



It will be seen that the larva of the gooseberry saw-fly 

 is not unlike a Lepidopterous caterpillar, and that its 

 appendages particularly resemble those of a caterpillar. 

 There is a difference, however, in the position of the 

 abdominal pseudopods, as will be seen by comparing these 

 two formulae : 



Thorax Abdomen 



Caterpillar 123 ..3456... 10 



Gooseberry saw-fly 123 .234567.9. 



In saw-flies which have abdominal pseudopods, and these 

 are the great majority, the number varies, but is never so 

 low as five pairs, the usual number in Lepidoptera ; more- 

 over, the second abdominal segment always bears pseudopods 

 in a saw-fly larva, if any are present at all — hardly ever 

 in a Lepidopterous caterpillar. 



We have said that after the fourth moult the larva ceases 

 to feed, enters the earth, and becomes a resting larva. At 



this time the black 

 spots disappear, or 

 become much re- 

 duced, and the 

 colour changes from 

 variegated green to 

 yellow, in conse- 

 quence of the empty- 

 ing of the alimentary 



Fig- 57— Resting larva of gooseberry saw-fly. X 5. canal. The head 



loses its dark colour, and becomes pale, showing up 

 the red mandibles and the black eye-spots. The mandibles 

 change their shape, becoming more pointed. In a few hours 

 the larva falls from the bush, enters the earth, and there 

 spins its cocoon in any suitable cavity. Occasionally it 

 spins upon the leaves of the bush. During the feeding 

 stage the salivary reservoirs become distended with fluid 

 silk, which is used up in spinning the cocoon. It is probably 

 a consequence of the loss of silk that the resting larva 

 contracts and becomes distinctly shorter. It rests in its 



