Junes. i9i8 Bocterial Disease of Gipsy-Motk Caterpillars 519 



that the number of organisms ingested in artificial infections is enormous, 

 and consequently more toxins are elaborated, which in turn cause more 

 striking changes. The pathology of the musculature is characteristic 

 enough, however, so that any one can diagnose the disease from sections. 

 On finding the muscles in the conditions illustrated by figures A and B 

 of Plate 54, one can safely predict that 5. disparts will be found in the 

 alimentary tract. 



At the end of this article is a detailed description of Streptococcus disparts 

 with an account of the media best suited to its cultivation. 



Recently Paillot ^ described a microorganism parasitic in gipsy-moth 

 caterpillars. He named the bacterium Diplococcus lymantriae after the 

 old generic name of the gipsy moth, Lymantria. The writer has care- 

 fully studied Paillot's description and finds absolutely no resemblance 

 between his organism and 5. disparis in either cultural or biochemical 

 characters. Moreover, D. lymantriae is not very pathogenic to the cater- 

 pillars, whereas S. disparis is highly pathogenic. 



The writer has searched the literature, but has been unable to find a 

 description of a bacterium which in any way resembles 5. disparis. For 

 this reason, and especially since the organism may prove to be of some 

 economic importance, its description as a new species seems justified. 



FIELD EXPERIMENTS 



During the summer of 191 7 Mr. A. M. Wilcox, of this Bureau, and the 

 writer conducted a large series of field experiments in Massachusetts in 

 connection with S. disparis. One important phase of the work consisted 

 in attempting to discover whether the organism occurred anywhere in 

 the gipsy-moth infested territory. Efforts to find the disease in 191 5 

 and 191 6 failed, and in 191 7 a much more systematic endeavor to find 

 the organism in the field, in places where it was not artificially introduced, 

 was unsuccessful. Hundreds of dead caterpillars from a large variety 

 of places were collected every week and brought to the laboratory for 

 study. The mortality was always found to be due either to parasitism 

 by the tachina fly Compsilura concinnata Meigen to other insect para- 

 sites, or to wilt or some disease other than the Japanese bacterial malady. 

 S. disparis was recovered from none of these localities, and therefore the 

 statement that the new disease has not occurred in this country in the 

 field prior to 191 7 seems justified. 



Another phase of the work consisted in introducing the disease by a 

 variety of methods in woods heavily infested by the gipsy moth. The 

 idea of the writer is not to attempt the extermination of the gipsy moth 

 with the new bacterium, although, of course, he would wish to do so, if 

 it were possible, but to approach the subject in the same spirit in which 



> Paiuot, a. microbes nouvbacx parasites des chenilles de lymantria dispas. In Compt. 

 Rend. Acad. Sci. [Paris], t. 164, no. 13, p. sas-S^?- i9i7- 



