June 3, 1913 Bacterial Disease of Gipsy-Moth Caterpillars 



517 



Table I. — Results 0/ infection of eight fourth-stage American Porthetria dispar larvcefed 

 with red-oak leaves sprayed with a y2-hour bouillon culture of Streptococcus disparis. 

 Bacterium isolated from alimentary tract of animal which had died from disease « 



o Three pupated and emerged. Eight controls accompanied this series, 

 emerged. Five dead animals tested and S. disparts recovered. 



All lived, pupated, and 



Table II. — Results of infection of eight fourth-stage American Porthetria dispar larvcefed 

 with red-oak leaves sprayed with a y2-hour bouillon culture of Streptococcus disparis 

 recovered from one of the dead animals used in previous experiments ^ 



o Two pupated and emerged. Eight controls accompanied this series. All lived, pupated, and emerged. 

 Six dead animals tested and S. disparis recovered. 



Table III. — Results of infection of 25 third- and fourth-stage American Porthetria 

 dispar larvce fed with apple leaves sprayed with a ys-hour bouillon culture of 

 Streptococcus disparis «■ 



» Twenty-five controls accompanied this series. One died of wilt; the remaining ones lived, pupated, 

 and emerged. In the infection experiment the two which died on the sixth day succinnbed to wilt (poly- 

 hedral disease); the remaining ones died of the new disease. The one which died on the ninth day, the 

 three on the eleventh day, the two on the thirteenth day, and the one on the sixteenth day were tested 

 and 5. disparis recovered. The remaining dead were merely examined microscopically. 



At the conclusion of each experiment it is stated that the dead animals 

 were "tested." This signifies that stained smears were studied, the ma- 

 terial was "plated out" on agar, and the species of bacteria isolated was 

 observed culturally and biochemically. (See description of S. disparis 

 on pages 520-521.) 



From an examination of Tables I to III it will be seen that the period 

 from infection to death varies considerably. This is probably due to 

 individual resistance or to differences in the number of organisms ingested. 

 Death may be expected any time after about 24 hours; indeed, it may be 

 postponed for as long as 16 days. In Experiment I three and in Experi- 

 ment II two animals lived and transformed into moths. At present no 

 definite explanation can be offered for this occurrence. These 

 five caterpillars became infected because the contaminated food was 

 never removed until nearly all of it had been eaten. By confining the 

 caterpillars in glass fruit jars having tin screw tops the food foliage 

 can be kept palatable to the animals for three and sometimes four days. 

 56112°— 18 4 



