1909.] PUBLIC DOCUMENT — No. 73. 55 



rangements with Dr. Clinton, the work on the brown-tail moth 

 fungus, for which facilities were furnished by the botanic 

 garden and the cryptogamic laboratories of Harvard University, 

 was not commenced until IMay 14, and material of the fungus 

 itself was not obtained until some days later. 



Provision had been made for obtaining material of the 

 fungus for use in artificial infections, by sowing resting spores, 

 by means of which it is carried over in nature from season 

 to season, in a breeding cage at the garden; but before any 

 diseased larvae appeared in this cage, several were found ready 

 to discharge spores on nests brought into the laboratory. By 

 means of these and others which in a few days began to appear 

 in the garden cage, a sufficient number of infected larvae was 

 obtained to enable Dr. Clinton to make a first distribution in 

 a badly infested tract at Concord. It was therefore not until 

 May 28 that a first distribution of infected larvae was possible ; 

 but even at this date it had become evident that the chances of 

 a successful termination of the experiment were small, owing 

 to the fact that the hot weather in May had advanced the sea- 

 son, as compared with that of the previous year, nearly two 

 weeks, so that by the first week in June the larvae were nearly 

 ready to pupate, and a sufficient number of generations of the 

 fungus between the first artificial infection and the period of 

 general pupation was not available; while the drought which 

 began in early June made the conditions as unfavorable as 

 possible for the purpose in view. It was further found that 

 in all the localities which were selected for the distribution of 

 artificially infected caterpillars the disease had begun to appear 

 spontaneously, so that such results as were obtained cannot 

 be definitely attributed to the artificial infections made in 

 these situations. 



The mortality observed among the brown-tail moths, though 

 very considerable (estimated by Dr. Clinton as from 10 to 80 

 per cent, in the various localities examined, with an estimated 

 average of from 30 to 50 per cent.), was checked so abruptly by 

 the dry conditions above mentioned, which began during the 

 second week of June, that many larvae were found later in the 

 month that had been killed and mummified by the fungus, al- 

 though, from lack of moisture, no discharge of spores from 



