KEROSENE AS AN INSECTICIDE. 155 



it as a substitute for flour in the application of arsenical poisons and 

 pyrethrum powder. On this subject Mr. Schwarz reports as follows : 



At first I selected dust from the nearest road at hand and sifted it through a very- 

 fine sieve covered with a quadruple layer of fine muslin. I found, however, that this 

 dust was largely comjjosed of particles of sand without any adhesive power whatever, 

 and which, moreover, rendered the dust very heavy and quite unsuitable for any ex- 

 periment. This sand is very fine, and I failed t o eliminate it by using addition al layers 

 of muslin. I did not succeed better with dust prepared from the dry clay so common 

 along the river bank near Sel ma. Finally I obtained a suitable very tine dust by 

 sifting the rich black earth, which of course I had previously well dried. This dust is 

 comparatively light, and of considerable adhesive power even in dry weather. 



While we attach but limited value to dust either for preventing the 

 moths from ovipositing, driving off the worms, or killing them in the man- 

 ner just mentioned, still it might prove valuable as a diluent for arsen- 

 ical poisons where flour and other diluents cannot be obtained, and 

 more attention ought to be paid to this cheap and easily obtainable 

 substance as a remedy for various insect pests other than the Cotton 

 Worm. The insecticide property of dust mentioned in this connection 

 is not peculiar to road dust alone, but is possessed by every substance 

 which adheres to the worms in a sticky, paste-like covering. Thus by 

 the application of flour stirred up in water many small worms may be 

 killed, and the only results obtained by our agents in the application of 

 diluted dough and yeast are attributable to their action in the manner 

 here alluded to. 



OILS AND ALLIED SUBSTANCES. 



KEROSENE. 



It is a well-known fact that this is a most powerful insecticide, and ex- 

 periment has shown that a fine spray of kerosene applied to the leaves 

 will kill all worms thereon in a remarkably short time. This deadly 

 effect is produced by contact, a very small quantity of the oil applied 

 to the worm causing death. We have thus a very cheap and sure rem- 

 edy, which, moreover, cannot be called poisonous to higher animals, but 

 unfortunately the oil has the same pernicious effect on the plant as on 

 insect life, and the problem is to apply it in such flue spray, or so much 

 diluted as not to injure the plant and at the same time touch every worm. 

 The finest spray, produced by a parlor atomizer, of the undiluted oil is 

 sufficient to kill the leaves, the cotton plant proving to be exceedingly 

 sensitive to the effect of the oil, much more so, in fact, than man 3^ other 

 plants. The use of the undiluted oil being, therefore, impracticable, 

 there remains only to try to apply it in dilution. The onlj' available 

 diluent hitherto known being water, a new difficulty arises, viz., to mix 

 the oil with the water so as to produce a homogeneous or nearly homo- 

 geneous mixture of the two. To a limited extent, and only on a small 

 scale, this can be accomplished by very violentlj^ agitating the mixture. 

 More useful, but also practicable only on a small scale, is the following 

 method, recommended by Mr. William Saunders, of the Department of 



