168 Annals Entomological Society of America [Vol. XIII, 



surroundings. Typically, heterometabola, except when aquatic, 

 retain the same environment throughout life and the adults face 

 practically the same ecological conditions as do the immature, 

 wings simply increasing the chances of survival. 



Insects with complete metamorphosis all differ from those 

 with incomplete, in one respect: to each individual .three 

 environmental problems are presented. The larva must find 

 an adequate food supply, the pupa protection against enemies 

 and hostile physical conditions, and the adult opportunity and 

 means for reproduction. The abundance of the available food, 

 which includes every kind of organic matter, elaborated in any 

 way by any vegetable or animal organism, reduces the com- 

 plexity of the situation. Rapidity of locomotion, however, one 

 of the most effective means of escaping adverse conditions, has 

 been uniformly reduced or lost in holometabolous insects. For 

 the latter, therefore, the problem of utilizing the food supply is 

 one of protection against enemies and weather during the period 

 of growth. 



If we now turn our attention to the position of the Lepidop- 

 tera among other holometabola we find that the four major 

 orders have solved this problem of protection in four different 

 ways. The Coleoptera use the combative method of fighting the 

 struggle for existence. Clad in armor in both larval and adult 

 stages they exist on the hardest wood, prey on the most agile 

 insects, or burrow within the soil. The Diptera, on the other 

 hand, have adopted the path of least resistance. While the 

 armed beetle larva hides in caves and burrows, the dipterous 

 maggot is concealed deep in rotting vegetation, in the stomachs 

 of mammals, or the body juices of other insects. Even the 

 predacious Syrphid larvae attack only the softest, most helpless 

 of all insects, the plant lice. 



Hymenopterous larvae, excepting the Tenthredinoidea, have, 

 if anything, gone farther. Many still "rustle for themselves" 

 but in the more specialized predatory families even the host 

 insects must be paralyzed by the parents before the larvee can 

 successfully attack them. Finally the last step is reached 

 among the bees and ants where the young must be fed, warmed 

 and cared for day by day, so utterly helpless that they can not 

 even be furnished with an adequate supply of food and left to 

 consume it alone. 



