284 JOURNAL OF ECONOMIC ENTOMOLOGY [Vol. S 



By confining beetles in a cage containing unsprayed leaves, and 

 also leaves sprayed with various combinations such as arsenate of lead 

 and water; arsenate of lead, water, and flour paste; arsenate of lead 

 and soap; lime-sulphur; and Bordeaux mixture; it was found that the 

 beetles fed much more freely on the unsprayed leaves than on those 

 sprayed with mixtures containing either soap, lime-sulphur, or Bor- 

 deaux. Leaves sprayed with the arsenate of lead and water and with 

 arsenate of lead, water and flour paste were eaten nearly as freely as 

 the unsprayed leaves. It is probable, therefore, that the addition of 

 lime-sulphur or Bordeaux mixture to an arsenical spray renders it 

 ineffective, since they are both distasteful to the beetle and help it to 

 avoid the poisoned leaves. Later observations tend to confirm this 

 conclusion. This last spring the writer was in an orchard where the 

 flea-beetles were very numerous. The owner of this orchard had 

 sprayed several rows of trees with arsenate of lead and water, and 

 several adjoining rows with arsenate of lead and Bordeaux. Two 

 days later dead beetles were lying thick on the ground under the trees 

 sprayed with the arsenate of lead and water, but hardly any could be 

 found under the trees in the rows sprayed with arsenate of lead and 

 Bordeaux. The spraying in this case had all been done the same day, 

 the spray applied in the same manner in both cases, and the beetles 

 were equally abundant in all the rows at the time the spraying was 

 done. The difference in results must therefore have been due to the 

 fact that Bordeaux was used in one case and not in the other. 



The beetles' habit of feeding almost exclusively on the under sides 

 of the leaves suggests the necessity of directing the spray upward, 

 rather than downward or horizontally as is usually done, especially 

 early in spring. In the spraying mentioned above, special care was 

 taken to cover the lower sides of the leaves, and the large number of 

 beetles poisoned in the one case is evidence that this method of 

 spraying is quite effective. 



In one experiment 24 trees were sprayed with arsenate of lead, 4 

 pounds; flour (made into a smooth paste by scalding), 8 pounds; and 

 water, 100 gallons. The spray was directed upward so as to cover 

 thoroughly the under sides of the leaves, no attention being paid to 

 the upper sides, with a pressure of about 150 pounds per square inch. 

 Two days later dead beetles were lying thick on the ground. On a 

 canvas about 90 square feet in area, which was spread under one of 

 these trees as soon as the spraying was completed, 720 dead beetles 

 were found two days later. It was estimated that an average of over 

 3,000 beetles to the tree had been poisoned in this way, and that this 

 number represented between 70 and 80 per cent of the beetles on 

 the trees before spraying began. These results also indicate that the 



