66 TRANSACTIONS OF THE ILLINOIS 



times were allowed to be destroyed indiscriminately j but as the birds * 

 diminished the insects increased, and to such an extent that destruction 

 to the crops was threatened, so the Governments passed laws protecting 

 and fostering the birds, when the insects decreased again. I can see but 

 one way to test this bird question : let the authorities stop the destruction 

 of birds, and have preserves established for the purpose of studying their 

 habits and their sources of food. We must do something, and this seems 

 to me the most feasible of any plan yet broached. 



I agree with Wier, except as to the little black beetles. 



In relation to the cabbage-butterfly, I will say that the true parasite 

 of the imported species {^Pieris rapes) has appeared in Illinois, which will 

 no doubt aid us another year in keeping this pest in check. Another one 

 from Europe has also been found. I think also that we have a species of 

 ichneumon that preys upon them ; I am not quite sure of this, however. 



I have observed the past season that the Pieris does not remain as 

 long in the pupal state in Southern Illinois as it does in New York, and 

 a striking difference between the imported and native species has also 

 been observed in the way the eggs are laid. We find the eggs of the 

 imported species deposited singly on both upper and under sides of the 

 leaf, while the native deposits in clusters and on the under side of the 

 leaf only. The butterfly of the imported species is very pugnacious and 

 is driving the native before it. The worm of the imported one is very 

 peaceful and quite sluggish, and in this respect both native and foreign 

 are alike. 



Pieris rapce, does not bore into the head ; another new but different 

 worm does bore into the head, however. Flat Dutch and Fotler's 

 Brunswick are freer from them than other varieties on account of the 

 solidity of their heads. 



Prof. Forbes. — I would suggest that thorough experiments be made 

 to determine the value of birds, as to which are the more or the less 

 beneficial or absolutely pernicious; this can be done only by long- 

 continued and careful experiments. A preliminary survey should, however, 

 be made by the examination of the contents of the stomachs of birds. 

 A preserve should be established where observations could be made, long 

 and patiently, and this could be done with but little expense to the State. 

 Taking my examinations of the stomachs of birds of the State as a whole 

 the result is somewhat in favor of the value of birds, but it is hard to tell 

 whether some birds do more harm than good. 



Dr. Thomas. — I would state that while I appreciate these examina- 

 tions made by Prof. Forbes, I think a law should be passed establishing a 



