MISCELLANEOUS INSECTICIDE INVESTIGATIONS. 5 
As will be noted, while the triplumbio arsenate of lead was very 
effective against the larvae, it was somewhat slower in its killing 
effect than the diplumbio and the mixture of diplumbic and triplumbio 
arsenate of lead. This held true in the other experiments that 
follow. Of the three commercial arsenates of lead, commercial (1), 
which consisted of the triplumbio form, required a greater length of 
time to kill the larva 1 than was required by the other two commercial 
brands, which consisted mainly of the diplumbio form. 
Arsenate of iron, both chemically pure and homemade, was used 
at double strength, owing to indications of slow killing effect in 
previous tests. At this strength it was somewhat slower than 
many of the other arsenicals. Like results will be noted in later 
experiments with this material. 
The arsenates of zinc were effective and seemed to be safe to 
use on the foliage. 
Arsenic sulphid, arsenic tersulphid, arsenic trioxid, arsenite of 
lime, and the arsenites of zinc were effective, but burned the foliage 
more or less seriously. 
Mercury bichlorid and zinc chlorid, while effective, were very 
injurious to the foliage. 
All the other compounds were ineffective. 
Experiment II. 
COMPARISON OF THE KILLING EFFECT OF VARIOUS ARSENICALS AND DOUBTFUL STOMACH 
POISONS COMBINED WITH LIME-SULPHUR SOLUTION ON LARVAE OF THE FALL WEB- 
WORM. 
In Table II are given the results of using lime-sulphur at the rate 
of 1] gallons to 50 gallons of spray in combination with all the 
materials used. Little difference was noted from the use of these 
combinations of lime-sulphur with the arsenicals. However, in 
case of the materials which had no effect on the larvae when used 
alone a marked difference was evident from the addition of lime- 
sulphur. In all cases the larvae were killed, the length of time of 
killing varying considerably with the material used. The difference 
no doubt was largely din 1 to the difference in chemical reaction 
between the material and the lime-sulphur. Lime-sulphur alone 
killed the 20 larvae in 15 days with only 0.7o square inches of foliage 
consumed. In Table II are shown the results. 
