THE GOOSEBERRY SAW-FLY 



but is not indigenous, having probably been introduced 

 into Britain with timber from Norway. 



There is, however, a common representative of this 

 Family Tenthredinidce in the South Country in the 

 person of the Gooseberry Saw-Fly {Pteronidea ribesii. 

 Fig. 49). The gregarious larvae will strip a currant or 



Gooseberry Oci^ii,'- 



gooseberry bush of all its leaves, and have a habit of 

 hiding their bodies on the edges of, or underneath, the 

 leaves. The adult occurs in April or May, and the 

 female deposits her greenish eggs on the leaves. The 

 larva feeds for about a month, and if not discovered 

 in time, much harm will have been perpetrated. After 

 having had its fill, the larva reaches the ground, spins 

 a cocoon, and pupates. The perfect insect, or imago, 

 emerges in about twenty-one days, and there are three 

 generations in a season. It is interesting to notice 

 that parthenogenesis occurs in this species, that is, 

 unfertilised females can produce fertile eggs. The 

 full-fed larva is light green, with orange colour on the 

 first and last segments, and a very large pale coloured 

 head, but at first it is profusely spotted all over with 

 black. It has three pairs of true legs, and seven pairs 



101 



