[ 294 ] 
34 
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Chalcis holes. 
Chalcis larvse- 
Acari, or unknown 
Coccinellae.. 
Eggs. 
86 
79 
102 
2 
16 
Whole number 
284 
Oct. 25th, examined a number of twigs obtained from different 
orchards in DuPage county : 
Whole number of scales...230 
Chalcis holes. 
Chalcis larvae. 
Acari, or unknown 
Eggs...-. 
87 
70 
58 
15 
Whole number.230 
Prom 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 under them, though most 
of them were more or less damaged, and in some of them the 
Chalcis larvae had commenced their work of destruction. 
The history of this little Chalcis-fiy 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 mytilaspidis , nob.) a, fly; b, an¬ 
tenna; c, larva. 
