A NEW BACTERIAL DISEASE OF GIPSY-MOTH 

 CATERPILLARS^ 



By R. W. Glaser, 



Entomological Assistant, Gipsy Moth and Brown-tail Moth Investigations, Bureau of 

 Entomology, United States Departinent of Agriculture 



INTRODUCTION 



During the summer of 191 5 a large series of eggs of the Japanese gipsy 

 moth (Porthetria dispar Linnaeus) were hatched. These eggs had been 

 obtained for the writer by Prof. Richard Goldschmidt from Ogi, Japan. 

 On reaching the third stage many of the caterpillars began to die of a pe- 

 culiar disease which the writer had never in previous years noticed in any 

 of his American cultures. The infection later spread to the American 

 race, and the most rigorous methods of isolation and disinfection had to be 

 inaugurated in order to save most of the cultures from extinction. The 

 disease was very soon controlled, and this led at once to a belief in its 

 bacterial origin, and its distinctness from wilt (polyhedral disease).^ 

 Anyone who has worked with wilt knows with what great difficulty this 

 disease is controlled once an epidemic gains a foothold. 



Inspired by the belief that this new disease might be used in combating 

 the gipsy moth in the field, the writer made a systematic study of it 

 during the seasons of 1915, 1916, and 1917. 



SYMPTOMS AND CHARACTERISTICS OF THE DISEASE 



When a caterpillar contracts this new disease, which may be provi- 

 sionally named the "Japanese gipsy-moth disease," it acquires a violent 

 form of diarrhea, loses its appetite, and finally ceases to eat. The insect 

 seems to lose all muscular coordination and usually crawls slowly to some 

 elevated place, where it soon dies. After death it hangs in a flaccid 

 manner by its prolegs, with an appearance of death from wilt. In 

 contradistinction to wilt, however, the skin does not rupture, but is 

 so tough that one can pick up and stretch the animal with considerable 

 force before the skin breaks. 



1 Contribution from the Bureau of Entomology, U. S. Department of Agriculture, in cooperation with 

 the Bussey Institution of Harvard University (Bussey Institution No. 140). 



* Glaser, R. W. wilt of gipsv-moth caterpillars. In Jour. Agr. Research, v. 4, no. 2, p. 101-128, 

 pi. 11-14. May 15, 1915. Literature cited, p. 127-12S. 



Chapman, J. W., and Glaser, R. W. further studies on wilt of gipsy moth caterpillars. In 

 Jour. Econ. Ent., v. 9, no. i, p. 149-163. 1916. 



Glaser, R. W., and Ch.\pman, J. W. the nature of the polyhedral bodies found in insects. 

 In Biol. Bui., v. 30, no. 5, p. 367-390. May, 1916. Bibliography, p. 383-3S4. 



Journal of Agricultural Research, Vol. XIII, No. 10 



Washington. D. C June 3, 1918 



ut Key No. K-6s 



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