NEW YORK STATE MUSEUM 



The larvae of insects present marked divergences from the normal 

 structure and occasionally appear to lack important organs. The head is 

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

 often very minute, the wings are wanting, as are also the true legs 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 

 ot the highest developed insects are the most helpless, degraded forms, 

 being dependent on the mother to place the egg where food is of easy 

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

 some instances is bestowed 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 existence, 

 some being much more powerful in the immature than in the adult condi- 

 tion. This is particularly true of the May Hies, some species of which 

 develop into a very short lived, weakly organized adult. 



Important groups of insects affacting 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 groups which have certain distinguishing features. 



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

 tribute two important groups, namely, the four winged gallflies or Cynip- 

 idae, and the s^wflies or Tenthredinidae. 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 experience, 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 addition to the 6 thoracic or true 

 legs, 12 to 1 6 abdominal prolegs. Several sawfly larvae are very voracious 

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

 Adirondacks. 



