PACKARD.] INSECTS OF THE FOEEST. 245 



change to pupoe in the autumn, while others wait till the fol- 

 lowing spring. The beetle appears in June. 



Now in the remarkable habits of these insects, we find a 

 variation in their mode of working corresponding to some 

 difTerence in the size and nature of the branch in which they 

 live. This is something quite different from the blind, unva- 

 rying instinct usually ascribed by the unthinking to the 

 lower animals. The oak pruner selects a fitting place in 

 which to la}^ its eggs, and because it does so for generation 

 after generation, no one can deny that there was not a time 

 when this habit was in process of formation, and gradually 

 established after a course of experiments continued through, 

 perhaps, many generations. Again, the borer itself is not 

 entirely the creature of circumstances ; there is some room 

 left for the exercise of what we may call judgment. The 

 incision it makes in the branch varies in depth with the size 

 of the branch, and it must exercise a certain, be it a mini- 

 mum, amount of reason to adjust its life vv^ith the ph3-sical 

 forces about it, in order that the life of the species may 

 be maintained. Doubtless it makes many mistakes, many 

 branches falling too soon or not falling at all ; many deaths 

 occurring from these mistakes. Unfavorable seasons, calm 

 weather, a too dry or too moist atmosphere, its parasites, 

 all conspire to reduce its numbers and render its struggle 

 for bare existence exceedingly precarious. But this is the 

 history of every species of animal. The life of each species 

 is a record of mistakes, and disease and often death in con- 

 sequence of those mistakes. And turning to the human 

 species, the philosophic historian of his race is forced to 

 confess that it is often by their misfortunes that races as well 

 as individuals of marked individualism have moulded their 

 characters. We submit, then, that these unusual instinctive 

 acts of the oak pruner have been in all probability gradually 

 acquired, after many trials, mistakes and failures, until the 

 peculiar habits distinguishing this species from its allies 



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