INSECTICIDES. 



427 



to stand for nearly three hours, to determine the difference 

 in action between this and the experiments where the poison 

 had not been allowed to stand. An oak branch was sprayed 

 with this mixture, and ten large fifth-molt caterpillars 

 placed upon it. July 21, the branch was resprayed on 

 account of heavy rain, and on July 25 the foliage became so 

 badly burned that the caterpillars were transferred to a 

 freshly sprayed oak branch. Seven of the ten began to 

 pupate, but of these only two emerged, and one of those 

 was imperfect. Foliage of the first branch was very badly 

 burned, while that of the second was in good condition. 



lbs. Paris Oreento 150 gal. Water. 



Xo. 40. — April 26, 1894. Ten caterpillars, three days 

 old, were placed on lettuce leaves which had been treated 

 with Paris green, in the proportion of IJ lbs. to 150 gal. 

 of water. One died on the first, one the second and six the 

 third day ; two escaped. 



Check experiment : none dead. 



Xo. 41. — May 9, 1894. Ten caterpillars, six days old, 

 were placed on lettuce leaves which had been treated with 

 Paris green, in the proportion of IJ lbs. to 150 gal. of 

 water. Five died the second, three the third and two the 

 fourth day. 



Check experiment : none dead. 



No. 42. — May 28, 1895. Ten caterpillars, of the first 

 molt, were placed on lettuce leaves which had been treated 

 with Paris green, in the proportion of 1^ lbs. to 150 gal. of 

 water. Four died the third, three the fourth and three the 

 fifth day. 



Check experiment : one died the fourth day. 



No. 43. — June 10, 1894. Ten caterpillars, of the second 

 molt, were placed on lettuce leaves which had been treated 

 with Paris green, in the proportion of 1^ lbs. to 150 gal. of 

 water. Two died the second, one the third, one the fourth, 

 one the fifth, two the sixth, two the seventh and one the 

 eighth day. 



Check experiment : none dead. 



No. 44. — June 21, 1894. Ten caterpillars, of the third 



