REPORT OF J. P. STELLE. [31] 



THE YEAST FERMENT REMEDY. 



Obedient to orders in '' Supplementary Instructions" I put tills proposed remedy for 

 the Cotton Worm to many careful tests, employing three grades of yeast, or " ferment," 

 in my exi)eriments. No. 1 was a duly prepared yeast obtained from a brewery; No. 

 2, the same, obtained from a bakery ; and No. 3, a preparation made by myself after 

 Professor Willot's plan as laid down on page 71 of Bulletin No. 3. The yeast was di- 

 luted with water to various strengths, and sprinkled upon the plants and worms, both 

 in the open field and uutier gauze-covered boxes. The boxes used were large dry 

 goods boxes from which both top and bottom had been removed. They were placed 

 over living plants in the tield that had been liberally stocked with worms, and sprink- 

 led with the preparations, after which a thin cotton gauze, as mosquito barring, was 

 tacked over the top of each. 



The closest jiossible attention was given to these experiments through an ample 

 lapse of time for their perfect development. Nothing resulted to indicate that the 

 remedy was of any value whatever. 



PYRETHRUM POWDER. 



The powder used by me in my exjieriments was the California preparation some- 

 times seen upon the market as " Buhach." I began operations by inverting two glass 

 tumblers upon several thicknesses of soft paper, and placing under No. 1 five grains 

 of pyrethrum powder, dry, and under No. 2 the same quantity mixed with water to 

 a thin paste. Next I XJlaced under each tumbler two lively Aletia moths taken from 

 my breeding-box. The r. oths flew up and took positions immediately under the bot- 

 toms of the inverted tumblers. 



One miuute, all the moths were seen to be shaking or twitching their wings. Five 

 minutes : all had fallen to the paper. When I struck upon the tumblers with my hand 

 they fluttered up, but immediately fell back again, having apparently lost the power 

 of holding to the glass with their feet. Fifteen minutes: both moths in No. 1 were 

 unable to fly up when I struck upon the tumbler, but lay upon their backs and moved 

 their feet sluggishly, as if in the act of walking. No. 2 flew up the sides of the tum- 

 bler and fell back as usual. Thirtj^ minutes : No. 2 could rise no more ; each of the 

 four was lying upon its back, slowly moving its feet. In six hours all were dead, 

 No. 1 dying about half an hour sooner than No. 2. 



This seems to prove that the dry powder is more prompt in its action than when 

 moistened with water. 



At early twilight I closed my windows and turned loose in my room six lively Aletia 

 moths, after having dusted upon the head and thorax o^ each a very small quantity 

 of dry pyrethrum i3owder. They flew up and settled about the ceiling and windows. 



irlve minutes: each showed that peculiar twitching of the wings that had been seen 

 early in the course of the preceding experiment. Fifteen minutes : three were down 

 on the floor unable to rise. Twenty-five minutes: all were down and helpless. I col- 

 lected them in an open wash-bowl ; next morning all were dead. 



Sprinkled two rows of cotton running across a square acre, with pyrethrum powder 

 in water at the rate of one-fourth of an ounce to the gallon ; also, two rows with the 

 same at the rate of half an ounce to the gallon. The plants were heavily stocked 

 with worms in almost every stage of growth^ it being late in the season when the 

 broods were not marked with much regularity as to time. The weaker solution 

 thinned out the worms somewhat, but did not give full satisfaction; the stronger 

 solution entirely cleared the plants — next day not a living worm was to be found upon 

 the rows sj^rinkled with the stronger solution, though there were jflenty of dead ones 

 to be seen, usually upon the ground. 



I made a dusting implement by fitting the pipe of a small hand-bellows into a small 

 tin box, and perforating the top of the box with many minute holes. A dry powder 

 l)laced in the box could be forced through the perforations by working the bellows 

 with care, thus enabling one to spread it quite thinly and evenly over the leaves of 

 plants. With this I dusted two worm-infested rows of cotton with dry pyrethrum 

 powder unmixed with anything, at the rate of about one pound to the acre, throwing 

 it as much as possible against the undersides of the leaves. This broiight no satis- 

 factory results, which was, I take it, on account of the extreme lightness of the pow- 

 der preventing it from flying with force sufficient to stick to the leaves, and also en- 

 abling a very large proportion of it to float ofl" upon the air. I subsequently applied 

 it in the same way mixed with dry London purple at the rate of one pound of the 

 purple to four ounces of pyrethrum. This gave it weight and consequently a better 

 sticking capacity. The result was very good — in from two to three days not a worm 

 was to be seen on the plants. 



I conducted many experinuuits with pyrethrum looking to a fixing of its volatile prin- 

 ciple, so that it might be applied in the ox^en field and made more fasting in its effects. 



