HYMENOPTERA 



245 



number of prolegs on the abdomen, and lack the hard shield usually 



found on the prothorax 

 of lepidopterous cater- 

 pillars. Most of them 

 feed on foliage, and many 

 are quite injurious. Sev- 

 eral species are soft- 

 bodied and covered with 

 a viscid, slimy matter, 

 which has given them 

 the name of " slugs." 

 Among the more com- 

 mon species are the 

 yellow-and-green currant 

 worms (Nematus ribe- 

 sn), which devour the 

 foliage of currants and 

 gooseberries, the rose- 

 slug (Endelomyia rosae], 

 which strips off the sur- 

 face of rose leaves, leaving them brown as if scorched, and the 



pear-slug (Eriocampa ce- 



rasi), which injures pear 



and cherry foliage in the 



same manner. Other spe- 

 cies often defoliate straw- 

 berry and raspberry bushes, 



and there are numerous 



species which may be 



found on various shade 



and forest trees, one of 



the most injurious being 



the larch saw-fly (Ly- 



gaeonematus erichsonii), 



which has defoliated and 



thus destroyed large areas 



of larch in New England 



and Canada. 



FIG. 386. The pear-slug 



a, adult saw-fly, female ; l>, larva with slime removed ; 



c, same in normal state ; d, leaves with larva (natural 



size), (a, b, c, much enlarged.) (After Marlatt, United 



States Department of Agriculture) 



FIG. 387. Pear-slug, illustrating method of ovi- 

 position and emergence of larva. (Enlarged) 



a, cutting of cell beneath epidermis of leaf, showing 

 the tip of the ovipositor ; b, the cell after the egg 

 has been deposited ; <:, same after the escape of the 

 larva. (After Marlatt, United States Department of 

 Agriculture) 



