82 THE CLASS OF INSECTS. 



to be converted into one or more aerial receptacles of spores." 

 (Leidy.) These fungi, so often infesting caterpillars, are hence 

 called "caterpillar fungi." They fill the whole body, distend- 

 ing even the legs, and throw out long filaments, sometimes 

 longer than the larva itself, giving a grotesque appearance to 

 the insect. Leidy has found a species which is very common 

 in the Seventeen-year Locust, Cicada septendecim. He found 

 "among myriads of the imago between twelve and twenty 

 specimens, which, though living, had the posterior third of the 

 abdominal contents converted into a dry, powdery, ochreous- 

 yellow, compact mass of sporuloid bodies." He thinks this 

 Cicada is very subject to the attacks of these fungi, and that 

 the spores enter the anal and genital passages more readily 

 than the mouth ; thus accounting for their development in the 

 abdomen. 



The most formidable disease is the " Muscardine" caused by 

 a fungus, the Botrytus Bassiana of Balsamo. It is well known 

 that this disease has greatly reduced the silk crop in Europe. 

 Balbiani has detected the spores of this fungus in the eggs of 

 Bombyx mori as well as in the different parts of the body of 

 the insect in all stages of growth. Extreme cleanliness and 

 care against contagion must be observed in its prevention. 



Among plants a disease like Muscardine, due to the presence 

 of a minute fungus (Mucor mellitopJiorus) , fills the stomach 

 of some insects, including the Honey-bee, with its colorless 

 spores, and greatly weakens those affected. Another fungus, 

 JSporendonema muscce, infests the common House-fly. 



Another Silk-worm disease called ' ' Pebrine" carries off many 

 silk-worms. Whether it is of pathological or vegetable origin 

 is not yet settled. 



There are also a few intestinal worms known to be para- 

 sitic in insects. The well-known "Hair-worm" (Gordius) 

 in its young state lives within the body of various insects in- 

 cluding the Spiders. The tadpole-like young differs greatly 

 from the parent, being short, sac-like, ending in a tail. Upon 

 leaving the egg they work their way into the body of insects, 

 and there live on the fatty substance of their hosts, where they 

 undergo their metamorphosis into the adult hair-like worm, 

 and make their way to the pools of water in which they live 



