ON SOME LEPIDOPTEROUS LARV^ 75 



On the other hand, when favourable natural causes have 

 produced an unusual abundance of any species, it is often 

 found that this very abundance attracts fresh enemies, 

 either mammals, birds, or parasitic insects, which speedily 

 reduce the numbers of the larvse to the normal point ; in fact 

 a year marked by vast swarms of any particular species is 

 often followed by a season of scarcity. Of course where we, 

 by a wanton and excessive destruction of bird-life, have 

 destroyed the balance of Nature, \^e have only ourselves to 

 thank if garden and orchard are infested by hordes of pre- 

 datory larvae. 



I may here observe that I have thought it better not to 

 deal with the lepidopterous larvse, which T wish to speak of 

 to-night, in the usually classified order, which is, by the 

 way, just now threatened with a far-reaching and revolu- 

 tionary change, based in great measure upon the pupal 

 characters. With such a difficult subject we have nothing 

 to do to-night ; it is quite outside our field of view — the 

 larva. 



I have therefore broadly grouped the larvae according to 

 their ways and means of protection, as these will be found 

 to be closely correlated with their habits, and at the same 

 time this grouping fits in sufficiently well with the generally 

 received classification. 



One of the most usual means by which the larvse of moths 

 are protected is by resemblance to twigs or branches, or by 

 the similarity of their colour to the leives on which they 

 feed. The great family of Geometers, Land Measurers, or 

 Measuring Worms, as they are called in America, from 

 their singular means of progression, or looper caterpillars as 

 we sometimes call them, are instances for the most part 

 of protection by resemblance to twigs. These caterpillars. 



