50 NATURAL ENEMIES OF INSECTS 
Fungous and Bacterial Diseases of Insects 
Fungous diseases of various kinds attack insects, and occasionally 
are responsible for their death in large numbers. A familiar example 
Fig. 54. — Tent Caterpillar, Malacosoma 
americana Fab., killed by a fungous 
disease. Original. 
is seen at the close of every 
summer when many of our 
common house flies may be 
observed clinging to the ceil- 
ing, their abdomens distended 
and covered with a fine, pow- 
dery substance, while a ring 
of the same light powder sur- 
rounds the insect’s body on 
the ceiling. 
Nearly every season speci- 
mens of the common tent 
caterpillar may be found hang- 
ing from a leaf or twig, the 
body misshapen and covered 
with a powdery growth. Mil- 
lions of brown tail caterpillars 
have been killed in the New 
England states in the last 
two years by a  fungous 
disease. 
Attempts have been made 
to propagate these diseases 
artificially. A fair measure 
of success has sometimes at- 
tended these efforts, but the 
undertaking is difficult, owing 
to the fact that certain con- 
ditions of weather and moisture appear to be essential to the 
growth of the fungus. 
Caterpillars of some species are attacked also by bacteria of one or 
