34r OYSTER- SHELL BARK-L0TT8E. 



Chalcis holes 86 



Chalcis larvae • ^'^ 



Acari, or unknown 102 



Coccinellse ^ 



Eggs ^5 



Whole number 'ib4 



Oct. 25th, examined a number of twigs obtained from different 

 orchards in DuPage county : 



Whole number of scales 230 



Chalcis holes 87 



Chalcis larvae 70 



Acari, or unknown 58 



Eggs ••• ^^ 



Whole number 2ao 



From this it appears that in the localities which I examined, 

 more than twice as many bark-lice were destroyed by Chalcides, 

 than by all other agencies combined. But the most important re- 

 sult is, that, of eight hundred and forty-four scales examined, only 

 fifty-seven, or about one in fifteen, contained any eggs for another 

 year's crop; and the* case is really much more decisive than ap- 

 pears from the statement as it here stands, because 1 have inclu- 

 ded all the scales which had any eggs uuaer them, though most 

 of them were more or less damaged, and in some of them the 

 Chalcis larvse had commenced their work of destruction. 



The history of this little Chalcis-fly furnishes one of the most 

 interesting chapters in the literature of economic entomology. It 

 had long been known to exist, by the smooth, round holes in the 

 scales through which it had escaped. But it was not till the pres- 

 ent season that I had an opportunity to trace the insect itself 

 through its changes and witness the mode of its beneficent opera- 

 tions. I have drawn up a brief sketch of its history for the De- 

 cember number of the American Entomologist, illustrated by a 

 figure of the fly and its larva. 



Parasitic Chalcis of the Apple Bark-louse (Aphelinus mi/tilaspidis, nob.) a, fly; b, an- 

 tenna; tf, larva. 



