336 
WISCONSIN STATE AGRICULTURAL SOCIETY. 
animals and plants are able permanently to hold their ground, 
year after year, upon a tract of land no larger than an ordinary 
state. 
To afford some practical idea of the number of enemies that 
often prey upon a single insect, we will now give a brief 
account, illustrated by figures, of a few of the various cannibal 
insects that attack the Colo¬ 
rado potato bug, either in the 
egg, larva or perfect state. The 
list might be easily swelled to 
over a score, but to avoid en¬ 
tering upon a multiplicity of 
details we shall enumerate only 
ten distinct species, Hitherto 
it has been supposed that there 
was no parasitic insect what- 
Colors—Gray, black and silvery white. ,, , , 
ever that preyed internally up¬ 
on the larvae of this potato bug; but we have ourselves bred 
from these larvae a parasitic two-winged fly (Tachina family, 
Fig. 46,) the peculiar habit of which is to attach its egg 
externally to the body of its living victim; which egg subse¬ 
quently hatches out, burrows into the body of the infested 
Fig. 4G. 
i-1 
Fig. 47. Fig. 48. Fig. 49. 
Colors—Pink Colors—Brick red, Colors—Brick red, 
and black. black and white. black and white. 
larva, and eventually destroys it, but not until it has gone 
under ground in the usual manner. The important and 
extensive family to which this two-winged fly belongs has 
hitherto been so little attended to by North American Ento¬ 
mologists, that we cannot satisfactorily identify it with any of 
the few prescribed species, and for the same reason we prefer 
not to name and describe it as a new species. 
In the egg state the Colorado potato bug is preyed upon by no 
