346 JOURNAL OF ECONOMIC ENTOMOLOGY [Vol. 10 



But little, if any feeding took place for the first 12 hours; from that 

 time on feeding was general, but restricted. On the morning of April 

 11, a period of 48 hours, practically all the caterpillars were dead. 

 The amount of foliage devoured was about equal on the two mate- 

 rials and comparatively slight on either. The foliage showed small 

 scattering spots of burn. By April 13, four days after spraying, the 

 foliage on both No. 1 and No. 2 was burned to a crisp. 



Experiment B 



May 6, 1916. Sprayed apple foliage in laboratory with the follow- 

 ing materials, allowed to dry and introduced approximately 1,000 

 half-grown caterpillars on each. 



No. 1. AS2O5 at the rate of 1.5 grams to 1000 c.c. H2O, plus lamp black at the 



rate of 2 grams to 300 c.c H2O. 

 No. 2. AS2O5 at the rate of 1.5 grams to 1000 c.c. H2O, plus lamp black at the rate 



of 1 gram to 300 c.c. H2O. 

 No. 3. AS2O5 at the rate of 1.5 grams to 1000 c.c. H2O, plus fuller's earth at the 



rate of 2 grams to 300 c.c. H2O. 

 No. 4. AS2O5 at the rate of 1.5 grams to 1000 c.c. H2O, plus fuller's earth at the 



rate of 1 gram to 300 c.c. H2O. 



As in Experiment A, the caterpillars were restless and refused to 

 eat for a few hours, but soon commenced to feed sparingly. 



Table Showing Rate of Kill of Materials 

 Material Number Dead 



May 7 May 8 May 9 Total 



No. 1 40 252 454 746 



No. 2 21 232 373 626 



No. 3 37 531 Practically 568 



all dead 

 No. 4 24 259 257 540 



Comparatively speaking, but little foliage was devoured. Most of 

 the caterpillars which remained on the foliage were decidedly sick by 

 the morning of May 8, and there was no feeding on the 9th. A num- 

 ber of caterpillars from each series dropped from the foliage without 

 feeding and crawled away, which accounts for the small totals com- 

 pared with the numbers introduced. The foliage showed small scat- 

 tered spots of burn the afternoon of May 8. May 10, the burn had 

 spread somewhat, though by no means as general as in Experiment A. 



These materials might be termed rapid killers; in comparison with 

 acid lead arsenate and calcium arsenate they apparently have a higher 

 toxicity. 1 However, at these dilutions there is too severe a burn for 

 field use. 



'Lead arsenate and calcium arsenate tests for toxicity were carried on at the same 

 time. 



