[22] REPORT 4, UNITED STATES ENTOMOLOGICAL COMMISSION. 
ried into the' chamber by rapid diffusion, and, affecting the worm, causes it to come 
forth from its concealment upon the moistened parts of the plant, where, by the con- 
tact of the liquid, it is poisoned to death. The extract made with ethyl alcohol is 
also volatile and produces this same effect, though in a less degree to the extent that 
its volatility is less than that of methyl alcohol. 
The extractive power of methyl alcohol on pyrethrum is so great that it is hardly 
necessary to apply any heat ; the alcohol may be allowed to stand twenty-four hours 
on the powder, being shaken up a few times and then the whole, i. e., both the ex- 
tract and the solid residue, may be mixed with water, so as to give 100 gallons to the 
pound of pyrethrum. 
I found that the use of the liquid is much to be preferred to the powder. It reaches 
all parts of the plant better ; it is more easily handled and it kills quicker. 
EXPERIMENTS. 
1. Sprinkled powder on half dozen Heliothis in cotton blooms in the field. 
In a few minutes they left the blooms, crawled upon the leaves, fell to the ground 
and attempted to crawl off ; before going far they stopped and rolled over, as if in 
pain, then crawled a little farther with further rolling and twisting. After some hours, 
they were considerably shrunken, and became of a light yellow color instead of green. 
I observed these until night ; when I left none were dead ; next morning, none of them 
could be found. From this single experiment, I would not have known whether the 
worms died and were devoured by other insects during the night, or whether they re- 
covered and made their escape ; but subsequent experiments satisfied me they must 
have died. 
2. I tried a similar experiment on Heliothis, which I brought into the laboratory, 
putting them in blooms and on leaves in such manner as to supply the natural condi- 
tions. I applied the powder as above at 11 o'clock a. m. They were affected as those 
in experiment (1,) except that they seemed to be more violently attacked. They 
were not dead late in the afternoon ; they were all dead next morning, the size of 
the worms when dead being less than half their size before the application of pyreth- 
rum. 
In these experiments, I was carefnl that some of the powder fell on each worm. Of 
course, this would not be the case in ordinary field-work. My object was to see if, 
when fairly applied, powder of this strength would kill insects. 
I fonnd that insects with a thick chitinous covering frequently flew away, not 
seeming to be seriously affected. 
I tried this powder on Cabbage Worms ; it kills them when it touches them ; but 
on cabbages the worms are so well protected by the width and arrangement of the 
leaves that many escaped. 
It did not protect the cabbage plants, except for a short time, from the flea beetle. 
3. August 27 I sprinkled extract pyrethrum, 1 part alcoholic (ethyl) extract to 20 
parts of water, on a cotton plant where there were three Boll Worms. One of these 
had penetrated a boll so far that only a small part was extended outside the boll ; 
other two were on the flowers. In five minutes the worms were rolling and twisting, 
fulling to the ground ; died in a few hours. 
August 30. Used same extract as above on three Boll Worms. Result substantially 
same so far as Heliothis was concerned. Two young grasshoppers were quickly killed, 
and a ladybird fell to the ground. It was not dead, but struggling, as if in pain, 
when night came on ; had disappeared next morning. 
4. September 17: In the following experiment I used some of the same extract 
spoken of in preceding experiment. The quantity this time was half pint extract to 
five pints water. I selected a spot in the cotton-field where Aletiae were tolerably 
numerous. There were three stalks of cotton growing close together, and the vines 
ot morning glory had densely intertwined themselves with these three plants, making 
the foliage very thick and hard to penetrate. I caught a number of Aleti® from other 
stalks of cotton and put them on these until I could count 120. In all this time 
neither I nor either of the gentlemen present to witness the experiment noticed a boll 
worm (Heliothis). I used a small fountain pump made by Rumsey & Co., Seneca 
Falls, N. Y. We sprayed the diluted extract over three rows for about 20 feet, throw- 
ing more upon the three plants mentioned than elsewhere. Whilst the spray was fall- 
ing upon this thick foliage I closely watched its effect ; to my surprise a large Helio- 
thifl appeared on a leaf, seeming to be bewildered and making rapid exertions to get 
off. On examination I found it had come from the interior of a full-grown boll on 
w hir-h it was feeding ; the orifice it had cut was on the upper side, and I suppose somo 
of t he fine spray passed through the orifice, and disturbing it in its excavations, caused 
it to come forth. Soon after it appeared it crawled on a leaf which had fceen slightly 
wetted with the extract, and in two minutes from the time the extract was thrown 
on the plants this Heliothis fell to the ground, and after convulsions, rolling, crawl- 
ing, twisting, w T hich lasted an hour and a quarter, it died. In four minutes about 
