1907. J PUBLIC DOCUMENT No. 73. 127 



sects is concerned. The important consideration for the taxpayer is, 

 whether these parasites, even if imported in large quantities, will ulti- 

 mately prove of material help in suppressing the moths; and it should 

 be borne in mind that this experiment is one wholly without precedent 

 in the annals of applied entomology. There never has been in the 

 history of the world an effort to import on a large scale the parasites 

 of any leaf-eating caterpillar. It therefore follows that, in the first 

 experiment of the kind ever made, every step must be proved before 

 those in charge can be positive of the results. From the present hope- 

 ful outlook, however, it seems most desirable that this work should be 

 vigorously continued during the next few years, and arrangements are 

 already completed for the importation and breeding of a much larger 

 number of parasites than heretofore during the coming summer. 



This experiment costs but little as compared with the remarkably 

 large sums of money spent in fighting the moths in field operations, 

 and it is to be hoped that sufficient provision may be made for carry- 

 ing on the work at least for three years more. 



FUNGOUS DISEASE OF THE BKOWN-TAIL MOTH. 



On page 127 of the last annual report of the superintendent, 

 attention was called to an interesting fungous disease of the 

 brown-tail moth caterpillars, which in certain localities was 

 very effective in destroying the insects in wholesale numbers. 

 Its effect was very noticeable on the large caterpillars. An 

 investigation of this epidemic by Dr. George E. Stone, botanist, 

 Massachusetts Agricultural College, showed that the active or- 

 ganism was Empusa aulicoe, Reichardt, a common parasite, 

 according to Thaxter, of caterpillars and grasshoppers. It is 

 also mentioned by Grevillius as being common in Europe among 

 brown-tail moth caterpillars, and often to such an extent as 

 to serve as a marked check on their outbreaks. 



Following the occurrences of this disease early in the sea- 

 son of 1905, it became evident on the appearance of the small 

 brown-tail caterpillars in the fall that the fungus was wide- 

 spread throughout the district, and was working with even 

 greater force on the young of the species than it had on the 

 larger ones earlier in the year. By the time the leaves began 

 to fall and the feeding season of the caterpillars was finished, 

 there came in from the entire infested district reports showing 

 that remarkably large numbers of the small caterpillars had 

 died on the outside of the winter webs, as a result of the dis- 



