70 



our knowledge of the economics of this because species several of tlie 

 facts mentioned above liave been either ascertained or verified during 

 the year by Chancellor Snow, Prof. Thaxter, or myself. 



The so-called Botrytis tenella has been extensively advertised in 

 Europe by a firm of Parisian chemists, who send out the spores in 

 plugged test tubes, at G francs a tube. I have obtained two of these 

 packages from these dealers — who, by the way, want an American 

 agent — and one directly from Prof. Giard himself. From these tubes 

 cultures have been made by Prof. Thaxter and by 3Ir. Marten in my 

 laboratory, and experiments have been tried with the product on the 

 white grub, for whose destruction this fungus is especially recom- 

 meuded, and on various other insect larvse. I may be permitted to 

 add that it has proven with us much less effective, even for the white 

 grub, than our own Sporotrichum. 



Perhaps the first international exchange of living insect fungi for 

 economic use was made this year with Prof. Giard, to whom I sent a 

 package of Sporotrichum in exchange for Botrytis tenella. I mention 

 this merely to suggest the possibilities evident in this direction. 



Another fungus insect disease, the so-called blue fungus disease of 

 the chinch bug, due to a species now called, on Prof. Thaxter's 

 authority, Empusa aphidis, has been handled chiefly by Prof, Snow, 

 who used it, with the other diseases of that insect, by the well-known 

 method of contagion, for the wholesale destruction of chinch bugs in 

 the field. It is incapable of artificial culture, but may x)erhaps be kept 

 ill hand alive in relatively small quantity by using hothouse plant-lice 

 as a medium. 



Upon the bacterial diseases of insects I do not know that anything 

 definite and conclusive has been done within the year. The discovery 

 reported by me in September, 1891, of the normal ami uniform occur- 

 rence of several species of bacteria in special appendages of the ali- 

 mentary canal of certain families of Heteroptera, at all ages of the 

 insect, has involved in doubt a good deal of our earlier work on the 

 bacterial diseases of Hemiptera, and greatly enhanced the difiiculty of 

 their investigation. I will mention here in passing, however, the observa- 

 tion recorded in the paper referred to, that cases of apparent disease 

 frequently occur among chinch bugs, in which the mucous membrane 

 of the alimentary appendages in question becomes completely disor- 

 ganized and broken up, with an accompanying increase in the number 

 of these bacteria. This is a point which we have carefully and repeat- 

 edly verified during the present season. 



A study of the bacterial diseases of the cotton boll worm is briefly 

 reported, but not fully described, by Mr. Mally in Bulletin No. 26 of 

 the United States Division of Entomology. One of these diseases is 

 there identified with the common white plague of the European cab- 

 bage worm and the cabbage Plusia, but economic experiments with 

 this disease seem to have had only negative results. 



