69 



life. The observatiou made some years ago that most Ooccinellidae 

 feed largely, and sometimes wholly, upon fungi of common ocfurrence 

 and easy culture, first suggested this idea to me, but I do not know 

 that it has ever been experimentally tested. 



Several of the plant parasites of insects, on the other hand, feed 

 greedily on very common substances, and may be kept in stock, conse- 

 quently, or made to multiply on occasion with enormous rapidity, and 

 so scattered broadcast where and when most needed. This is true of 

 all the bacterial germs of insect disease thus far studied, and also of 

 certain higher fungi infesting insects. 



On two of the latter work of importance has been done during the 

 year — on a species chiefly studied abroad, known in thepapers of Giard, 

 of France, as Isaria densa, and in those of Prillieux and Delacroix as 

 Botrytis tencUa; and on an American species whose determination, like 

 that of the preceding, the botanists interested have not yet finally set- 

 tled on, but which now passes among us as Siwrotrichum globuHfermn. 

 Some laboratory work and a good deal of field experimentation with 

 this latter fungus is reported by Chancellor Snow, of Kansas, in his 

 voluminous and important rej)()rt published in April, 1892. It was also 

 studied briefly by Prof. Eoland Thaxter, in 1891, by whom the fact of 

 its ready culture on agar was determined; and it has been the subject 

 of almost continuous observation and experimentation at my own office 

 and in tlie field since May 11 of last year. This fungus, which springs 

 from minute white "spores," or so-called conidia, penetrates the living 

 insect, and finally imbeds the dead body of its host in a thick felt of 

 white fibers, which become covered with myriads of white or slightly 

 yellowish spores collected in globular heads. It does not form resting 

 spores, belonging, in fact, to an order of fungi in which such spores 

 have never been found, but it may nevertheless be preserved in a living 

 state for many months — certainly over the winter — by simply drying 

 out the ripe conidia. We have so preserved it, in fact, for an entire 

 year, and have found by experiment that the vitality of its conidia is 

 proof against at least ordinary winter temperatures, and against a 

 summer heat of 104° F. It attacks a great variety of insects of all 

 orders, but with various degrees of virulence, according to the kind of 

 insect, the resisting jiower of the individual, the condition of the 

 weather, and apparently also to some extent according to the previous 

 history of the spores used for infection. That is, it seems likely at 

 present, although not certainly proven, that spores from artificial cul- 

 tures on nutritive media take effect on insects less promj)tly and cer- 

 tainly than those derived from growths on insects themselves. 



This fungus may be cultivated in large quantity very readily in dis- 

 infected fruit jars on corn meal soaked with beef broth, the growth 

 forming a thick layer of dust-like spores on the surface, which may be 

 brushed or scraped off and preserved for use in homeopathic vials, 

 plugged with cotton. I give here this sketch of the present state of 



