43 
3:25. One seems to be a little uneasy ; others manifest no anxiety. 
3:42. The one in boll has turned around and is poking its head out of the bolls; 
another has moved and gone into a blossom; the others same as before. 
4:10. One is feeding ; all the others quiet and not feeding. 
5:00. One feeding ; others no change. 
5:50. None feeding. 
September 21. Four still in place, all feeding; the other has left the plant. 
September 23. One still in place, but has about destroyed its boll. The others 
have done so and are gone. 
The record of the experiment with two parts decoction and one part rain water is 
- omitted because of the similarity of results to those of Experiment 16. 
CHECKS ON EXPERIMENTS 15 AND 16. 
September 20. At first three, but later five more worms were marked as checks. 
2:30. One entirely in boll, feeding ; another, nearly mature, resting and not feeding ; 
a third, very young one, is feeding. 
5:00. Checks all in place feeding. 
5:50. All but very young one feeding. Made a search for more worms; found five, 
all of which are in bolls feeding, 
September 21. One still in boll, but not feeding. 
The small worm has bored through a form and is feeding. The nearly matured 
worm has destroyed its boll and has gone away. 
The result of all the experiments with pyrethrum is, on the whole, 
negative. Before treating more fully of the results of the experiments 
it must be stated that the corn plants, cotton bolls, and Boll Worms were 
more thickly and thoroughly dusted or sprayed than it would have 
been possible to do by dry method of application which would be inex- 
pensive enough to be practical. There is a special difficulty in the case 
of cotton. At the time when the powder would be most efficient, that 
is, when the worms are yet less than half grown, they are found princi- 
pally at work in forming blossoms and very young bolls. In these the 
involucre so completely and effectually inclose the portions in which 
the worms are at work that it is practically impossible to reach them. 
It is well known that the young form or boll is sensitive to excessive 
rains, and their involucres, it seems, are to a great extent a provision of 
nature to protect the tender young bolls from such injury. To what- 
ever extent this may be the case, it is certain that their involucres make 
it exceedingly difficult to reach the forms and bolls beneath them by 
any of the methods of spraying, and therefore also to all decoctions or 
solutions of whatever kind. 
Upon corn before it has tasseled the powder may be used with greater 
success, as will be seen from a study of Experiments 1to6. From these 
we find that a certain benefit of about 30 per cent. is obtained, with a 
possible benefit of about 47 per cent. This last is too high, however, as 
some of the worms which leave do so enly temporarily and to recover, 
after which they return. We also find thatthe young worms are much 
more susceptible, or at any rate less able to resist the effect of the pyre- 
thrum. Consequently of the worms killed, the great majority were half 
or less than half grown. From the behavior of the grown or nearly 
