NEW YORK STATE MUSEUM 



The larvae of insects present marked divert^ences from tlie normal 

 structure and occasional!}' appear to lack important t)rgans. The head is 

 usually present, the eyes are simple, sometimes absent, the antennae are 

 often very minute, the winijs are wanting, as are also the true leijjs in many 

 families. The abdomen is relatively much longer, and in certain groups at 

 least is provided with false legs or prolegs, which are of material service 

 in locomotion. It may be stated as a general rule, that the larvae of some 

 of the highest developetl insects arc the most helpless, degraded forms, 

 being dependent on the mother to place the c^g where food is of easy 

 access, or else they can attain maturity only with paternal aid, which in 

 some instances is bestowetl by a nurse form. Larvae; of the more lowly 

 organized insects are better able to provide for themselves, and those of 

 many species are relatively well equipped to meet the struggle for e.xistence, 

 some being much more powerful in the immature than in llie adult contli- 

 tion. This is particularly true of the May t^ies, some species of which 

 develop into a very short lived, weakly organized adult. 



Important groups of insects a.fecting forest trees. A great many insects 

 occur on or in our different native trees and shrubs, though comparatively 

 few of them are of much economic importance, and these in turn belong 

 to still fewer important grou])s which have certain distinguishing features. 



The bee family or four winged insects, known as Hymenoptera, con- 

 tribute two im])ortant groups, namely, the four winged gallflies or Cyni]j- 

 idae, and the sawllies or Tcnthredinidae. The former are not easily 

 distinguished as adults, though the deformities they produce in various 

 plant tissues can be confused only with those caused by certain other groups, 

 and then, after a little ex])erience, the galls of one group can easily be sepa- 

 rated from those of another. The sawflies are, many of them, leaf feeders 

 and some, gall makers. They may be readily distinguished in the larval 

 stage because of the many legs, having in acKlition to the 6 thoracic or true 

 legs, 12 to 16 abdominal prolegs. Several sawfly larvae are very voracious 

 and defoliate large areas ; for example, the well known larch sawfly of the 

 Adirondacks. 



