USE OF KEROSENE EMULSIONS AGAINST THE WORMS. 159 
hardly felt. Moreover, Professor Comstock's " emulsion" may have been less perfect 
than that osed l>y ourselves. The kerosene water was applied in the following exper- 
iments by means of a hand-atomizer, because from former experience I felt convinced 
that the oil can successfully be applied only in the form of the finest spray. Refined 
kerosene was used, instead of crude coal oil, because the former was more readily 
procured at Selma than the latter. From my experience with the crude coal oil in 
1879, I am inclined to think that there is not much difference between the two, either 
in regard to insecticide property or to their injurious effect on the plant. The chief 
difficulty to overcome iu the application of kerosene being the susceptibility of the 
plant, a series of experiments was first carried on to ascertain the proportion of the 
oil that could be applied without harm to tho plant. This was in the first part of 
September, when but very few worms were at hand. 
The emulsion was first diluted with five times that amount of water, thus giving 1 
part of the oil to 19 parts of milk and water; then with ten times that amount of 
water, and then used in still weaker dilutions. That the stronger mixture considera- 
bly scorched the plant was to be expected, but I would mention in this connection 
that a mixture of 1 part of kerosene to about 85 parts of water, whit h was incident- 
ally applied to a few corn-stalks and cow POM, did not seem to injure those plants. 
The limit where the «epray is less injurious to the plant begins with a mixture of about 
1 part of oil to 190 parts of water, but I eannot give in exact figures the mixture that 
can safely be applied to 1 he plant, as much depeidson the amount of the tluid actually 
applied. With a small hand-atomizer t he leaves nearest at hand receive a much larger 
amount of the fluid than those farther oil*, the force of the spray which strikes fullest 
the nearest leaves undoubtedly increasing the inllucnce of the oil. A mixture of 1 
part of the oil to lbO parts of milk and water, when moderately applied, is not injuri- 
ous to the leaves, in theee and the above-given figures ] have not included the exoeea 
of the oil which floats on the surface of t he mixture, and which I took care not to ap- 
ply to the plant. How much this excess is in proportion to the amount of oil used in 
preparing the emulsion I had no means to determine, but the amount of oil actually 
applied to the plants is at any rate smaller t ban the fig ires given above. Old leaves 
and bolls are the least liable to be injured by the kerosene spray : very young shoots 
and squares somewhnt more so, while young h aves fully developed and blossoms are 
most readily affected. In bright, hot weather the effect of the oil on the plant is risi- 
ble in a few hours, dry and crisp spots appearing on the leaves, and extending more 
and more, according to the amount of strength of the kerosene mixture. In cloudy 
weather the effects are less marked, and appear much later. Another series of experi- 
ments was carried on with a view of ascertaining the minimum amount of the oil m-ees- 
sary to kill the worms. Pure kerosene, or strong kerosene water, when sprayed upon 
the worms, has very much the same effect as benzine, young worms collapsing at once 
and dying in less than two minutes. Old worms are not so quickly killed; they do not 
show any signs of pain, and die without falling into violent convulsions. Theetl'ects 
of diluted kerosene water on averagc-si/ed worms arc not instantaneous, as with 
pyrethrutn, but if the worms are not effected within 16 minutes after application they 
have either not come into contact with the oil, or the mixture was too weak to have 
any effect. For very young worms, i. c, not over two days old (in the month of Sep- 
tember), a very weak mixture seems to be sufficient, but with the growth of the 
worms the resisting power is considerably increased. The mixture of 1 part of the 
oil to 1G0 parts of water is not sufficient to kill the average-sized worm, if applied in 
very fine spray and in moderate quantity; that of 1 part of oil to 120 parts of water 
is sufficient to kill the worms, but in all cases where I applied this mixture so as to 
kill the worms the leaves were considerably injured. 
The improvement made in the atomizing machines, which obviates 
entirely the danger of clogging, suggests another method to lessen the 
injurious influence of the kerosene on the plant, viz., by the addition of 
a quantity of very finely sifted wood ashes to the kerosene water, the 
