140 REPORT 4, UNITED STATES ENTOMOLOGICAL COMMISSION. 
more tender leaves ; but it Las, so far as our experience goes, no influ- 
ence on the unopened blossoms, 46 the squares and bolls, and this slight 
injury is much less serious than that which would have been caused 
by the worms. With the improved machines and with some practice 
the best arsenical poisons can always be so applied that they will effect- 
ually destroy the worms within forty-eight hours and without injury to 
the plants. If the plant be injured to any considerable extent the 
fault will lie either in the mode of application or in the inferior quality 
of the poison. 
Most of these arsenical poisons can be applied to the leaves either in 
water or dry, but some of the compounds are prepared so as to be used 
only in the former manner. 
Dry application. — When applied in powder the poison must be 
mixed with other ingredients, in order to render it sufficiently econom- 
ical and to avoid injury to the plant. The ingredients should mix readily 
with the poison 5 they should be cheap and, in the application from 
above, as far as possible adhesive, in order to prevent their being washed 
away by the rains. Of the various ingredients that have been used with 
success common flour gives most satisfaction, though it is somewhat 
expensive. Flour not only mixes most readily and homogeneously 
with the poison, but possesses also great adhesive qualities, even with- 
out further admixtures. Other materials used with success as dilu- 
ents are land plaster (gypsum) and cotton-seed meal, both being very 
cheap in some sections of the South, and to be recommended during 
dry weather, but having the disadvantage of being much less adhesive 
than flour. Both materials can, however, be advantageously used when 
mixed with the flour, the proportion being immaterial, provided the 
flour occupies the greater bulk. Finely-sifted wood ashes are not readily 
mixed or kept mixed with the much heavier arsenical poisons, and, hav- 
ing little adhesiveness, are not to be recommended alone, but are im- 
portant when combined with flour. 
By the admixture of about one-third of wood ashes to two-thirds of 
flour, the cost of the application is not only considerably lessened, but. 
another important advantage is obtained. The action of rain and dew 
converts the flour on the plants into a kind of paste, which, while it ad- 
heres firmly to the leaves, is somewhat injurious by excluding the air 
and by increasing the caustic action of the poison. Both these difficul- 
ties are measurably overcome by the admixture of wood ashes, and the 
good results obtained in Texas in the application of various arsenical 
poisons are largely due to the prevalence of the use of such ashes. A 
good supply can be collected during the winter, at no expense and with 
but little trouble. 
The substitution of common road dust for the diluents mentioned 
above has been taken into consideration, and we have carried on experi- 
ments as to its feasibility. The results show that very finely-sifted 
dust, which contains as little sand as possible, may, if nothing else is at 
