THE GIPSY MOTH AS A FOREST INSECT. 3 



are decidedly satisfying, and the State of Massachusetts and the 

 United States Department of Agriculture have no cause to regret 

 having undertaken the unexpectedly formidable task of parasite 

 importation. Within a territory centering a Httle to the northward 

 of Boston, it may be conservatively stated that fully 50 per cent of 

 the eggs, caterpillars, or pupae of the gipsy moth, in the aggregate, 

 were destroyed by imported parasites in 1912. The territory over 

 which the imported insect enemies have spread is not yet very exten- 

 sive, but it is extending notably from year to year, and there is every 

 reason to believe that the mortality to which the gipsy moth is 

 already subjected in this central portion of the infested area will 

 eventually be considerably increased throughout its whole extent. 

 Some additional work will be done toward assisting in the dispersion 

 of certain species, and it may be that a new attempt will be made to 

 import under more satisfactory conditions certain others which appear 

 not to have established themselves as the result of earUer attempts. 

 Otherwise the work of parasite importation may be considered as 

 completed. 



THE 'wilt" DISEASE OF THE GIPSY MOTH. 



More than to the parasites, more than to the perfection of the 

 methods of artificial suppression, the amelioration m conditions is 

 due to the ''wilt" disease. This is a malady similar to or suggestive 

 of the flacherie of the silkworm. According to recent investigations 

 it is due to parasitism by a bacterium which has been described under 

 the name of Gyrococcus jiaccidifex by its discoverers, Messrs. Glaser 

 and Chapman, workmg under the direction of Dr. W. M. Wheeler, of 

 the Bussey Institution, While it is not positively'' proved that this 

 bacterium is the cause of the disease, there are no good grounds for 

 doubting and many for believing that it is. Confirmation is expected 

 as the result of further cooperative investigations now under way by 

 the Bureau of Entomology and the Bussey Institution. 



Although we know very little of the bacterium, we know much of 

 the malady. Accordmg to the most trustworthy observers it first 

 appeared about 1903 or 1904 in certam of the worst infested forests, 

 and by 1907, when the present writer first became associated with the 

 gipsy-moth work, it was everywhere in evidence throughout the 

 mfested area. It seemed slightly to increase in the years immediately 

 following and to have reached a climax about 1911. At the present 

 time, fortunately, there is nothing to indicate that it is at all likely 

 to become much if any less effective in the immediate future. 



We do not yet know how the caterpillars originally become infected, 

 but once infected there is hardly room for doubting that the organ- 

 ism itself is conveyed from one generation to another through the 

 Q^g. Simple infection is by no means sufficient to cause death. On 



