INSECTICIDES. 487 



caterpillars of all sizes below the third molt were then 

 placed upon the twig, and sacked in by drawing a bag, 

 made of cheese cloth, over it, and tying the open part 

 closely around the base of the twig, to prevent the escape 

 of the caterpillars. Sixty per cent, of the feeding was upon 

 the unpoisoned and forty per cent, upon the poisoned por- 

 tion of the leaves. 



Experiment 2fb. 5. Three large willow leaves were 

 painted with Paris green, in the proportion of 3 Ibs. to 150 

 gal. of water, as follows: on leaf No. 1, three transverse 

 bands ; on leaf No. 2, three oblique bands ; on leaf No. 3, 

 a band one-fourth of an inch in width around the entire 

 margin of the leaf. Each leaf was then placed in a box with 

 a full-grown caterpillar. Leaf No. 1 was eaten equally on 

 the poisoned and unpoisoned areas ; leaf No. 2 was eaten 

 wholly upon the unpoisoned parts ; leaf No. 3 had the mar- 

 gin eaten in two places. 



Experiment No. 6. Three willow leaves were prepared 

 in the same manner as in the preceding experiment, except 

 that, besides the Paris green, 5 Ibs. of lime were added to 

 the water. Leaf No. 1 had a long, narrow strip eaten from 

 the margin, passing through the ends of the three trans- 

 verse bands of poison ; leaf No. 2 was eaten equally on the 

 poisoned and unpoisoned parts ; leaf No. 3 was eaten deeply 

 on the margin. 



Experiment No. 7. Three willow leaves were prepared 

 as before, using arsenate of lead, in the proportion of 6 Ibs. 

 to 150 gal. of water, instead of Paris green and lime. Leaf 

 No. 1 was eaten equally from the painted and unpainted 

 portions ; No. 2 was eaten in the same manner ; and No. 3 

 had the margin eaten in two places. 



Experiment JVb. 8. A small twig of oak, bearing six 

 leaves, was sprayed with Paris green, in the proportion of 

 10 Ibs. to 150 gal. of water, and another twig, bearing the 

 same number of leaves, was left unsprayed. Both were 

 enclosed in a sack with ten full-grown caterpillars. July 

 15. The greater part of the feeding was upon the unsprayed 

 leaves. July 16. More was eaten from the unpoisoned 

 than the poisoned leaves, yet six of the caterpillars had died. 



