290 



THE AMERICAN ENTOMOLOGIST. 



The result of the experiments is, that 

 the fungus in the form of active beer from 

 sugar produced no deaths, and that ten 

 per cent, of the worms fed on cotton 

 sprinkled with yeast died. This List was 

 about one-fourth of the mortality in con- 

 nection with yeast last year. As the di- 

 lution of the beer was followed by total 

 absence of mortality, and the dilution of 

 the yeast was accompanied by a reduction 

 of the mortality to one-fourth, the ad- 

 hesiveness of these menstrua, in clogging 

 the bodies and spiracles of the larvaj, and 

 in thus interfering with the function of 

 moulting, may be a sufficient cause of the 

 deaths of larvre and pupse observed in 

 both years. 



I desired to carry on similar experiments 

 in the field, but the season and circum- 

 stances of a personal nature prevented. 

 A single trial on a small scale, was made 

 on worms colonized on some cotton plants 

 in my garden. They fed from three to 

 six days on plants sprinkled with both 

 beer and yeast. Ten chrysalids were 

 gathered from the plants and placed in 

 boxes. They seemed very healthy and 

 none died. 



In conclusion, I think these experiments 

 furnish no ground for hope of successful 

 attack on the Cotton-worm with Veast 

 Ferment. 



EXPERIMENTS BY PROF. A. J. COOK, OF 

 L.\NSING, .MICH. 



September ^t/i, 1880. — I placed twenty 

 squash-bugs in each of four boxes, two of 

 which were closed, and the others covered 

 with wire gauze. Ten of the insects in 

 each box were yet immature, the other ten 

 were imagines. I also placed fresh squash 

 leaves in each box. The contents of two 

 of the boxes, one of them closed and the 

 other covered with gauze, were thoroughly 

 sprinkled with yeast diluted with tepid 

 water in the proportion of one part of 

 yeast to four of the water. The insects in 

 the other boxes w'ere simply for compar- 

 ison, and received none of the yeast liquid, 

 though the leaves were sprinkled with 

 water. I also treated some bugs which 

 thickly covered the ground beneath a 



squash vine with some of the yeast liquid. 

 In one week fresh leaves were added to 

 all the boxes, when the contents of each 

 box were sprinkled the same as before. 

 The bugs beneath the vine also received 

 a second application of the yeast. 



Daily examinations showed no deaths 

 in any of the boxes, though some of the, 

 pupse in every box changed to imagines. 

 I could see no evidence that any of the 

 bugs which were unconfined under the 

 squash vine, and treated witli the jeast, 

 were in any way injured. 



The same set of experiments was tried 

 with the potato-beetle {Doryphora \o-Iin- 

 eata Say), except that the leaves were re- 

 newed daily, and moistened, or rather 

 drenched, each time with the yeast liquid 

 or water. In the two weeks three of the 

 larvae in the boxes with no yeast died, and 

 five in the other two boxes. At the end 

 of tlie two weeks eight of the larvK in the 

 boxes whith contained the yeast had en- 

 tered the earth, and eleven of those in the 

 other boxes had done the same. Upon 

 digging these up, they all seemed in good 

 condition. So far as I could judge, the 

 imagines in the boxes, and the larvre and 

 beetles on the vines, which also recei\'ed 

 two applications of the yeast at an interval 

 of a week, received no injury from the 

 treatment. 



The same experiments were tried with 

 the caterpillars of the Cabbage-butterfly 

 i^Fieris rapce). During the first twenty- 

 four hours two of the- larvae changed to 

 chrysalids in three of the boxes, and three 

 in the other one of the closed boxes which 

 had received the yeast. Before the expiration 

 of the two weeks, all had changed to pupse, 

 and not one had died. Those larvse which 

 had been sprinkled on the cabbage plants 

 received no apparent injury. 



Sprigs of Alder {Aliins serrulata) thickly 

 covered on the underside with a wooly 

 plant-louse ^Eriosoina tessellnta Fitchl, were 

 dipped into the yeast licpiid September 8th, 

 and again September 15th, without any 

 perceptible injury. 



The weather during these experiments 

 was quite warm and pleasant. 



