THE SEMITBOPICAL ARMY WORM. 67 
on the vines and only a few live ones, buf the same condition- were 
observed on the check row.-. The experiment was an absolute failure. 
Experiment No. 11. — July 29, plants were sprayed with copper 
arsenite mixture at the rate of 15 ounces to 50 gallons of water. In 
this case \\ ounce- of copper arsenite and 1 quart of thick lime v 
used with 5 gallons of water. Two day- later the -pray showed better 
than in experiment No. 10 because of an abundance of lime and was 
very finely and evenly applied to the leaves. Four larva- were dead 
on a few plant- examined against 32 living Prodenia and 3 living 
sweet-potato sphinx-moth larvae (Phlegethontius convolvnli L.). 
August 0. this -pray >till remained on the foliage, seeming to 
adhere well, but the experiment was a failure in killing larvae. 
Experiment Xo. 12. — July 20. plants were sprayed with arsenate of 
lead. 3 pounds to .50 gallons of water, applied as in previous experi- 
ments with lead arsenate. There was no rain for 24 hours. On a few 
plants examined three days later 41 dead larvae were found and 49 
living, an observed death rate of less than 50 per cent. It should be 
pointed out at this time, however, that it is difficult to find dead larvae, 
as they sometimes dry up or crawl away. 
August 2. the vines were almost free from larva?. The experiment 
was pronounced very successful. 
Experiment Xo. 13. — July 30. arsenate of lead. 2 pounds to 50 gal- 
lons of water, was used without ensuing rain. In some row- exam- 
ined August 1 about 20 per cent of the larva 1 were dead ; in others 48 
per cent, 54 per cent, and 01 per cent were killed in two days. August 
5, these rows appeared entirely free from larva unless closely in- 
spected, when only 5 or 6 could be found to a row. These might have 
crawled from unsprayed weeds or other plant-. 
Ex peri an nt X<>. 14. — July 30. arsenate of lead, 3 pounds to 50 gal- 
lons of water, was used. Three days later 84 per cent of the larva 
under observation were destroyed, the rows being quite clean. In 
both of these experiments. 13 and 14. many dead larva were found in 
rows not -prayed, as many as rive rows away from the sprayed one-. 
Experiment Xo. Id. — August 7. arsenate of lead. 2 pounds to 50 
gallons of water, was sprayed by a laborer, under supervision. It 
rained at 1 p. m.. but the spray remained on the leave- in large 
amounts and. for having been applied by an inexperienced hand, was 
well distributed. In this experiment, for some reason, the first four 
row- sprayed at one filling of the tank produced quite a number of 
burned leave-. This was attributed to a possible mistake in weigh- 
ing out the chemicals. It did not. however, permanently injure the 
plants. 
Caterpillar- in the la-t I experiments, supposedly of the third gen- 
eration, were very small, not over one- fourth or one-third of an inch 
in length. As a consequence they were quickly killed, large numbers 
