74 EBE1UIARTS OUTLINES OF 



the Ninth Report of the State Entomologist of Illinois, by 

 Dr. Thomas, may be of interest to many readers: 



"CLIMATIC INFLUENCE." 



" Dampness is undoubtedly the most potent natural 

 agent in keeping them in check. 



Although they may have hatched out in excessive num- 

 bers, yet if a rainy season follows soon afterwards, they 

 will be destroyed to a very large extent, and the invigorated 

 vegetation will bid defiance to the feeble attacks of those 

 that remain alive. Like other insects their breathing ap- 

 paratus consists of tubes that permeate the body, connect- 

 ing with opening or breathing pores along the sides of the 

 body, one on each side of a segment. 



The moisture taken in by inspiration in all probability 

 produces disease, or at least in some way prevents the free 

 passage of the air and thus lessens the vitality. 



Excessive changes during the winter also appear to have 

 a tendency to destroy the vitality of the eggs. That those 

 of the red-legged and other allied species, which are some- 

 what boreal in their habits, can withstand a greater degree 

 of cold, is undoubtedly true, but they are certainly affected 

 by sudden and considerable changes. 



