[32] REPORT 4, UNITED STATES ENTOMOLOGICAL COMMISSION. 
While not positive, I am strongly inclined to the opinion that I have hit upon some- 
thing that will prove all that is required in that direction. It consists in simply mixing 
the powder with a solution of starch prepared and cooked as for use in the laundry, 
though made considerably thinner. A common paste, or a mere mixture of raw flour 
and water will not answer ; it must be "starch," a cooked solution, which is almost 
entirely transparent. 
Several times, just before leaving Texas, I put this preparation to test with fine 
results, though time did not admit of my making the experiment as thorough as I 
could have wished. The experiments that I did make consisted in sprinkling cotton 
plants with the starch and pyrethrum mixture, and then stocking them with worms 
two or three days afterwards. In each case the worms fed upon the starched leaves 
and died. 
I expect this to cross the views of many who hold that pyrethrum does not kill by 
going into the stomach ; I shall not contend that it does. Ml I Mow about the mat- 
ter is that the worms fed upon my pyrethrum and starch-sprinkled plants and died 
very soon afterwards. It is evident that the starch drying over the particles of py- 
rethrum had sealed them up, and protected them from the atmosphere. Each par- 
ticle was inclosed in a minute capsule, as it were, and it does not appear impossible 
that the worm, in its feeding, may have cut open one of these capsules and unwit- 
tingly liberated the death-dealing principle confined within, thus exposing itself to 
the effect without having eaten any of the contents. 
On reaching home I found some very large caterpillars (Sphinx catalpcv) feeding 
upon my seedling Catalpa trees in the nursery bed, and wishing to see what pyreth- 
rum would do for these worms I deposited a mere speck of the powder upon the heads 
or bodies of some of them. In about five minutes they had discovered that some- 
thing was wrong, and were beginning to flirt themselves about after the manner of 
such worms when a parasitic fly is troubling them. A green juice was forced from 
their mouths and thrown over their bodies, but all in vain — in a few hours they were 
dead. And the singular manner in which they disposed of their own "mortal" re- 
mains interested me exceedingly — they never fell to the ground, but invariably hung 
their heads over the petiole of a leaf, let go with all their feet, and died, leaving their 
bodies thus strangely suspended, where they were to be seen for days afterwards. 
Wishing to further test my starch and pyrethrum mixture, I selected a young ca- 
talpa, growing some distance away from the main bed, and sprinkled the under sides 
of its leaves with the mixture, intending to stock it a few days later with worms. 
That night heavy rains fell ; in fact it rained heavily and almost incessantly for sev- 
eral days, at the end of which time the worms were about all gone for the season. 
Of course it was but reasonable to suppose that the mixture was all washed from the 
young catalpa under experiment, and that, therefore, my test was ruined ; it was now 
too late to begin it anew. Finding three worms on some of the other plants I placed 
them upon the catalpa under mention and went about my business, giving the mat- 
ter no particular thought further. This was in the morning j in the evening I chanced 
to pass the same way, and, judge of my surprise, there hung the three worms from 
the leaf-stalks of the young tree, dead. On examination I found where each had eaten 
a small portion of a leaf. 
OTHER VEGETABLE POISONS. 
I went to Texas entertaining great hopes that I should find among the native plants 
of that State some substitute for pyrethrum, or, at least, something that would ap- 
proach towards it in value as an insecticide. Under this stimulus I put to practical 
test a large number of plants, some of them botanically related to pyrethrum and 
many otherwise. My course of procedure was to dry and pulverize the flowers and 
leaves, and apply the jjowder so obtained on the plan usually resorted to with pyreth- 
rum. I regret being forced to report that my efforts in this direction were wholly un- 
rewarded ; I found nothing that deserved to rank higher than a mere temporary an- 
noyance to Cotton Worms, driving them, to some extent, but not killing them. 
ARSENICAL POISONS— LONDON PURPLE. 
It has been published that London purple suspended in water at the rate of half a 
pound of the former to forty gallons of the latter, and sprinkled over the plants, would 
prove entirely effoctual as a poison for destroying tho Cotton Worm. In the hands of 
a professional scientist so small a proportion of poison might bo mado to act very well, 
but experience and observation in Texas has convinced mo that it is too small for 
general use among planters, especially with the rnde kind of machinery now cojn- 
monly employed for putting it upon the plants. Three-fourths of a pound to forty 
<...! (ii :i proportion small enough lor the poison. This will destroy tho worms, and 
if well ;i:h1 evenly put on i\ill never injure the plants — in fact, ouo pound to forty 
gallons Will WOlk DO injury to the plants worth naming if kept well stirred up in the 
water, and thrown finely and evenly over the cotton. 
