44 ENTOMOLOGY. 



and death. It is very contagious, being transmitted to 

 healthy larvas by the infection of their food either with 

 fresh excrement or with the dust of infected silk-worm 

 nurseries of the previous year. Forbes has studied the 

 flacker ie of the caterpillars of Pier is rapes and of Da tuna 

 ministra, and has shown that the spontaneous disease due 

 to a species of micrococcus "may be unquestionably con- 

 veyed to other lepidopterous species, and even to the white 

 grubs;" he has also seen wide-spread epidemics of flacherie 

 in the caterpillars of Pieris rapec, of Pijrameis cardui, 

 and of Nephelodes viola ns, and has met with it here and 

 there in numbers of other caterpillars and hymenopterous 

 larvas, as well as the chinch-bug; while from the researches 

 of Cheshire and Cheyne "foul-brood " in bees is now known 

 to be produced by Bacillus alvei. 



The disease known as " muscardine," often causing wide- 

 spread destruction to both larval and adult insects, is 

 caused by fungi, or moulds, which are often visible to the 

 naked eye. They are species of Botrytis, Isaria, Cordyceps, 

 Empusa, Entomophthora, etc. The spores of these moulds 

 enter the bodies of their hosts through the spiracles, being 

 inhaled, not penetrating through the mouth; their spores 

 also germinate on the surface of the body, sending slender 

 threads through the skin into the body; these threads 

 separate into small single cells (cylindrical "conidia"), 

 which, growing and dividing again and again, derive their 

 nourishment from the blood and tissues, the victim dying 

 a slow death, after which the body becomes filled with the 

 mycelial threads, which finally, as in certain species of Isaria 

 and Cordyceps, send up long filaments, more or less club- 

 shaped, when they are called " caterpillar fungi." A large 

 proportion of the flies and other insects in different stages 

 found in autumn dead and stiff on fences, weeds, trees, 

 and within houses, are victims of Entomophthora. 



De Bary says: Should we carefully look in the leaves 

 and moss on the ground in forests in the wet portions of 

 the year, we should be astonished at the number of insects 



