The Saw-Flies 



bushes in different parts of 

 the country, while the large 

 and handsome Cimbex 

 americana, known as the 

 American saw-fly, is fre- 

 quently found upon elms, 

 willows and birches in 

 sufficient numbers to al- 

 most entirely defoliate 

 them. The yellow-spotted 

 willow slug {Nematus ven- 

 tralis, Say) is a common 

 enemy to willows in the 

 United States. 



The life histories of all 

 of the species just men- 

 tioned are well known, but 

 there are very many forms 

 which need careful study. 



Nematus simiiaris. (After Comstock.) 



Fig. 46. — Nematus marylandicus=Pachynematus 

 extensicollis. (After Marlatt.) 

 75 



