THE ENTOMOLOGIST. 



Vol. XV.] APEIL, 1882. [No. 227. 



ON THE DISEASES OF LEPIDOPTEROUS LARVAE. 

 By a. B. Earn. 



Having been looking through the manuscript of a translation 

 which I made some years ago of M. Pasteur's masterly work on 

 ' Diseases of Silkworms,' I thought that parts of it might have 

 some practical bearing on the rearing of lepidopterous larvae 

 generally, and I accordingly send for publication the following 

 hints on the disease with which, it appears to me, lepidopterists 

 are most concerned. 



M. Pasteur attributes the disasters which, for the last twenty 

 or more years, have attended commercial silkworm-rearing, to two 

 principal diseases, namely, to '' pehrine,'" or spotted disease, and to 

 "Jlacherie." To sericulturists the former of these diseases is of 

 the greater importance, while to rearers of our indigenous larvae 

 the latter appears to be the greater evil. 



Pebrine is not only a contagious, but essentially an 

 hereditary, disease, and (as will be readily understood) entails 

 great loss where the same species has to be reared for an 

 indefinite number of generations, and where, as in the case of 

 the silk-moth, wild specimens cannot be taken to deposit eggs for 

 fresh rearings. Those entomologists who rear specimens from 

 the eggs for their collections do so for a few generations at most, 

 and start again from time to time with eggs from wild specimens ; 

 thus almost, if not entirely, avoiding a disease which becomes 

 more formidable to each successive generation. Flacherie, 

 although it may be hereditary, may on the other hand be 

 suddenly developed in a brood of larvae, and kill every individual ; 



