THE SAIV-FLIES 



(Super-family Tenthredinoidea.) 



The saw-flies derive their name from the fact that the ovi- 

 positor of the female is peculiarly constructed, so as to act like a 

 saw. There are two saws set side by side in a groove under- 

 neath the body and can be shoved out and moved up and down. 

 They are used to make the proper aperture in leaves or other 

 vegetable tissues in which the eggs are placed. The head and 

 thorax are wide and the base of the abdomen is not slender. 

 The front shanks bear two spurs. 



The eggs are, as just indicated, laid in plant tissues, in 

 apertures made by the female saws. 



The larvae as a rule are remarkable from their resemblance 

 to caterpillars. Some of them look so much like cutworms that 

 one might almost expect to breed moths from them instead of 

 flies. They have, however, from twelve to sixteen prolegs, in- 

 stead often, which is the usual rule with the caterpillar. Many 

 of them also have the habit of curling the body around so as to 

 embrace the twig upon which they may be walking. Many of 

 them feed exposed upon the leaves of plants in much the same 

 way as do caterpillars. Others, however, are covered with slime 

 and look more like slugs than like insect larvae, while still others 

 are covered with a white, waxy excretion which completely 

 disguises them. 



There are a few leaf-miners in this group, while in the family 

 Nematidae are many gall-makers. A few make cases in which 

 they live. Nearly all descend to the surface of the ground to 

 transform to pupae, and spin silken cocoons about themselves. 



This super-family is particularly well represented m the 

 United States, and its species in fact seem to be more abundant 

 in temperate and cold regions than in the tropics. About two 

 thousand species have been described. 



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