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 famihar example 



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- 

 appear to be essential to the 



Fig. 54. — Tent Caterpillar, Malacosoma 

 americana Fab., killed by a fungous 

 disease. Original. 



ditions of weather and moisture 

 growth of the fungus. 



Caterpillars of some species are attacked also by bacteria of one or 



