PYEETHEUM AS USED AGAINST THE COTTON WORM. 173 



Experiment 2, August 27. — The same mixture applied with the bellows while going 

 slowly between the rows. A large proportion (estimated at two-thirds) of all the 

 worms on the plants were affected, but most of them had recovered the next morning. 



Experiment 3, August 27. — The same mixture applied with the hand. I had seen 

 this method in use in Texas, where flour and Paris green were used, and convinced 

 myself that it was an excellent and very economical method of applying dry powders 

 to high plants. I found, however, to-day that it requires some practice to distribute 

 the mixture evenly and economically. The result was about the same as in Experi- 

 ment No. 2. The mixture is evidently too weak if applied in moderate quantity. 



Experiment 4, September 4. — Pyrethrum 1 part, mixed with 10 parts of flour, applied 

 immediately after preparing, by means of the bellows. Comparatively few worms on 

 the plants, and no very young ones. Again, about two-thirds of the worms affected, 

 of which none or very few recovered. This mixture is evidently strong enough to 

 kill all the worms with which it comes in contact, though it was distributed in small 

 quantity. 



Experiment 5, September 4. — Pyrethrum I part, mixed with 15 parts of flour, applied 

 with the bellows, in part thickly, i. e., walking very slowly and using the bellows 

 freely, and in part very slightly applied. In the former case the mixture is as efficient 

 as that mentioned in Experiment 4, about two-thirds of the worms being killed ; in 

 the latter case a great proportion of the worms recovered. 



Experiment 6, Septembers. — Finely-sifted wood-ashes were substituted for the flour ; 

 ratio, 1 part pyrethrum to 10 parts of ashes. Applied with the bellows. Eftect the 

 same as in Experiment 4. The mixture is much lighter than flour, and spreads more, 

 but for this reason is not useful in windy weather; moreover, the preparation of the 

 wood-ashes is somewhat troublesome, as they must be sifted through a very fine sieve. 



Experiment 7, September 21. — Finely-sifted prairie soil was substituted for the flour: 

 1 part of xiyrethrum to 10 parts of soil. The mixture could not be applied by means 

 of the bellows, as it is too heavy; neither can it be applied by means of the sieve;, as 

 the two materials separate at once, the powder coming to the surface. It was finally 

 applied by throwing it with the hand, but it is evident that even then it is inferior 

 to flour and ashes, owing to its weight, which prevents its spreading and flying about 

 like the much finer and lighter flour. Otherwise, the mixture acts as powerfully as 

 that of pyrethrum and flour mixed at the same rate. 



i xperiment 8, September 21. — The same mixture as in experiment No. 1 applied after 

 it was left standing in a tight glass jar ever since August 27. Applied in moderate 

 quantity by means of the bellows. Worms very plentiful and mostly small. Again, 

 about two-thirds of the worms were affected, of which only a small proportion, if any, 

 recovered. The mixture is evidently by far stronger now than when freshly prepared, 

 and would undoubtedly be strong enough for average-sized worms. 



Experiment 9, September 26. — A small remnant of the mixture used in experiment 

 No. 8, which had been diluted, September 21, wdth about one-half the amount of flour, 

 was applied by means of the bellows. Worms very plentiful, and of all sizes. When 

 applied thickly the mixture still kills the small worms ; the larger ones that were 

 affected had, with few exceptions, all recovered the next day. WTien applied slightly, 

 even a portion of the smaller ones recovered; very small worms were, however, still 

 destroyed. 



N. B. — Full-grown worms are not taken into consideration in these experiments, as 

 they usually recover, unleSvS they get a very large dose of the mixture. A number of 

 trials in and out doors proved that for newly-hatched worms a mixture of one part of 

 pyrethrum to 20 parts of flour applied slightly and immediately after preparing is 

 amply sufficient. In these experiments, I used both the Californian buhach and im- 

 ported insect powder (furnished to the Commission by Messrs. Lehn & Fink), with- 

 out noticing any difference in efficacy between the two. 



Prof. E. W. Jones obtained very similar results, fle writes, ^* On« 

 part of Pyrethrum to 20 parts of wheat flour, thoroughly mixed and 



