EXPERIMENTS WITH PYRETHRUM. Lt 
_3,00.—Still no change. 
September 22, 9.30 a. m.—No motion left except a very slight oceca- 
sional twitching of the anterior prolegs. 
2. PARALLEL EXPERIMENT IN OPEN AIR. 
September 20, 11.45 a. m.—A larva similar in all respects to the pre- 
ceding was dusted in the same manner with the same powder, in the 
same quantity, at the same time. 
In 10 minutes it began to show signs of uneasiness. In 13 minutes 
began to struggle. The spasms increased in violence until 12.50 when 
they began to subside. There were still strong writhings at 3.30, and 
the body had only just begun to contract; while the confined worms 
had reached a similar condition at 12.50. 
At 9 a. m., September 21, the body had shrunken enormously, but 
there was still motion of the entire body. 
3.00 p. m.—No perceptible change. : 
September 22, 9.30 a. m.—Dead. This seems strange in view of the 
fact that the confined larvie which were strongly influenced by the pow- 
der at a much earlier period are still alive. 
EXPERIMENTS 3 AND 4. 
The following experiments were made with nine samples of powder : 
1st, the ordinary powder sold by Cutler Bros. & Co., of Boston, next, 
five samples labeled Cutler Bros. No. 1, No. 2, No. 3. No. 4, and No. 5, 
sent to the Department for comparative test; 7th, pyrethrum imported 
by Lehn & Fink, of New York City, in 1881; 8th, the 1882 importation 
of the same firm ; and, 9th, a powder made from flowers raised by Pro- 
fessor Riley in 1882. 
In experiment 3, six young larvee of Hyphantria textor, about one- 
fourth grown, were placed in each of nine labeled, closed tin boxes 
(11x8.5x3.5 em.), and a small quantity of each sample of powder was 
dusted on the dorsum of the anterior abdominal segments of the worms 
in each box. 
In experiment 4, three half-grown larve of the same insect were used 
in the same boxes and dusted in the same manner. Each worm received, 
as nearly as could be judged by the eye, the same quantity of the pow- 
der. 
