16 BULLETIN NO. 3, DIVISION OF ENTOMOLOGY. 
EXPERIMENTS WITH PYRETHRUM. 
We treated so fully of this insecticide in our annual report for 1881-2 
that the value of the powder and the modes of using it are now pretty 
well understood. The following account of experiments made by Mr. 
Howard will, however, prove interesting, as we had them instituted in 
order to show how the different larvee experimented with were severally 
affected by it. 
1. SPECIAL EXPERIMENT WITH CUTLERS’ POWDER NO. 1. 
September 20, 11.45 a. m.—Three healthy. half-grown larve of the 
Fall Web-worm (Hyphantria textor) placed in small glass tumbler, and 
a very small quantity of Cutlers’ No. 1 puffed on the anterior abdomi- 
nal segments of each; tumbler covered with glass slip. 
In four minutes one seemed affected; moved the head quickly from 
one side to the other, arched the back, and made rapid jumping move- 
ments as if trying to get rid of the powder. In 6 minutes all were sim- 
ilarly affected. At 7 minutes the one first mentioned was struggling 
violently and incessantly, jumping and writhing the whole body, now on 
its back and again on its side; no intervals of rest except momentary 
in this extremely rapid motion. 
In ten minutes became quieter, but was still bending the body in all 
directions ; incessantly writhing like a mammal poisoned with strych- 
nine. 
12.2.—Motions have become more spasmodic and jerky, and have lost 
to certain degree the smoothly writhing character. 
‘12.10.—Motions much slower and consist of a slow writhing of the 
whole body. 
12.18.—Motion still slower; the true legs trembling violently at in- 
tervals. 
12,.28.—The motion of the body has become very slow, but the legs 
are constantly twitching. The rectum is somewhat everted and the ab- 
dominal segments have become somewhat contracted. 
12.50.—The body is still more contracted, though still moving slightly, 
the legs still trembling somewhat. 
- 1.40.—The abdomen is still more contracted, but a slight motion is 
left, which shows that the final paralysis is that of exhaustion rather 
than of tetanus. | 
2.00.—Apparently almost dead; only a slight occasional motion of 
prolegs and mouth parts, with an occasional twitch of one of the true 
legs. 
3.20.—A very slight motion still perceptible; the bodies have 
shrunken to very small proportions. 
September 21,9 a, m.—Still a slight motion of legs and mouth parts, 
and one moves also one of its prolegs. 
1.15 p. m.—No change. 
