82 THE CANADIAN ENTOMOLOGIST. 



develop are abundant, the reproduction is an agamous one ; in the fall, 

 when insects become scarce, a sexual generation appears, which produces 

 oospores not germinating before the following spring. 



Mr. Giard believes that Tarichium megaspermum, the parasitic fungus 

 of the caterpillar of Agrotis segetum, and first described by Dr. Cohn, 

 could be used by farmers as a very important poison to destroy those 

 obnoxious insects — the more as O. Brefeld rTas proved by conclusive 

 experiments that the caterpillar of Pieris brassicce is very easily infested 

 by sprinkling with water in which spores of E. sphaerosperma (the para- 

 site of this species) are put in. Therefore the mummified caterpillars 

 filled with spores should be collected in winter for use the next spring 

 against this species. (The same has been suggested as long ago as 1874 

 by Dr. John L. LeConte.) The Entomophthera seem to attack by preference 

 the caterpillars of the double-brooded species, which pass the winter 

 without transforming in the chrysalis state. Mr. Giard explains thus the 

 casual rarity of some very common species of Chelonia. The hypothesis 

 of O. Brefeld that Tarichium megaspermum of Agrotis could be perhaps 

 only a different form of Empusa muscce is rejected by Mr. Giard, he hav- 

 ing discovered, as he submits, the Tarichium state of Empusa muscce, 

 which was not known before. The opinion that both forms of a fungus 

 develop exclusively on the same animal, similarly as other parasitic 

 insects, can, until it is proved by doubtless evidence, hardly be accepted. 

 We know well that the different stages of entozoa develop in very different 

 animals, and the presumption that fungi follow a similar course is at least 

 probable. 



There are published objections against my proposition to use the yeast 

 fungus tor destruction of insects. All are based upon the same fact, that Dr. 

 Bail's views concerning the identity of some fungi are not accepted by Botan- 

 ists. As the number of students of microscopical fungi is rather limited, and 

 as I have never studied them, I used the excellent chance to rely upon 

 the views of my savant colleague, Prof. Farlow, which he had kindly com- 

 municated to me. Therefore I stated as a fact that " Dr. Bail's views 

 are now not accepted by prominent Botanists," and further that " this 

 question is without any influence regarding my proposition." I believed 

 it to be fair to state that actually Dr. Bail has discovered the yeast fungus 

 to be poisonous to insects, and therefore I was obliged to quote the ways 

 and the experiments which had led him to this discovery. As Dr. Bail 

 had not suggested the use of the yeast for the destruction of insects — 



