sleeved in ten caterpillars. On the 8tli, seven died, and the last one 

 on the 17th. 



June 3. Sprayed a branch of an apple tree with arsenate of lead 

 in water in the proportion of | lb. to 150 gal., and the next day 

 sleeved in ten caterpillars. The first one died on the 6th, and the 

 last one on the 17th. 



June 3. Sprayed a branch of an apple tree with arsenate of lead 

 in water in the proportion of -^^ lb. to 150 gal., and the next day 

 sleeved in ten caterpillars. On the 8th, the first one was dead, and 

 the last one died on the 16th. 



June 3. Sprayed a branch of an apple tree with arsenate of lead 

 in water in the proportion of ^ lb. to 150 gal., and the next da^^ 

 sleeved in ten caterpillars. One caterpillar died June 6th, one on the 

 8th, one on tlie 9th, one on the 10th, two on the 11th, one on the 

 13th, and the last one on the 20th. 



CONCLUSIONS. 



A careful examination of all the details of this work, some of 

 which do not appear above, leads to the conclusion that the smaller 

 proportions, as f pound or less to 150 gallons of water do not kill 

 the caterpillars as quickly as is desirable, for so much time elapses 

 between the application of the insecticide and the death of the cater- 

 pillars, that many of them might wander away from the poisoned 

 food when not confined ; also heavy rains might wash the poison off 

 so thoroughly that the caterpillars could recover and pass their 

 transformations. 



The larger proportions seem unnecessary and would, of course, be 

 rather expensive for general field work, but some such proportions 

 as 1, 1^, or 2 pounds to 150 gallons of water would prove entirely 

 satisfactory so far as we can judge from these experiments as well as 

 from other very extensive experiments which have been performed 

 on the gypsy moth, both here in the lusectary and at Maiden in the 

 field. 



P^xperiments were performed on the Colorado potato beetle {Dory- 

 phora decemlineata) , with arsenate of lead in the proportions of J, -^q, 

 |, ^, f , |, 1, 1^, 2, 3, and 6 pounds to 150 gallons of water. Por- 

 tions of potato stems were set in bottles of water, under breeding 

 cages in the Insectary, and nine partly grown larvae of this insect 



