20 BULLETIN 352, U. S. DEPARTMENT OF AGRICULTURE. 
one orchard. The trees were 4 years old and of Early Richmond 
and Montmorency varieties. The former variety was used almost 
exclusively in the experiments. 
ARSENATE OF LEAD. 
KILLING STRENGTH. 
In order to determine the amount of poison necessary to kill the 
cherry leaf-beetle, trees were sprayed with various strengths of arsen- 
ate of lead on June 11. Two, 3, 4, 5, and 6 pounds were used to 50 
gallons of water; one-half nau ei i was added to each of these 
mixtures. In addition mixtures at the rate of 3 pounds to 50 gal- 
lons and 5 pounds to 50 gallons, to which had been added 1% gallons 
of molasses, were applied. To supplement the conclusions on the 
effect of the various mixtures drawn from observation of the beetles 
on the trees sprayed, about 100 beetles were confined in a bag on a 
branch of one tree sprayed by each of the different mixtures. No 
burning of foliage followed the application of any of the solutions 
used. 
The various arsenate of lead and lime mixtures were ineffective in 
killing many of the beetles. The stronger solutions—4, 5, and 6 
pounds to 50 gallons—were repellent and consequently to an extent 
protected the trees. The weaker solutions—2 and 3 pounds to 50 
gallons—were ineffective even as repellents, for the beetles confined 
in bags on trees thus sprayed fed without apparent inconvenience. 
The beetles confined in bags on the trees sprayed with the stronger 
solutions, especially 5 and 6 pounds to 50 gallons, fed but little, 
although they were confined for a week. A negligible number of 
beetles, never 10 per cent, was found dead in the bags. 
The sweetened arsenate of lead used at the rate of 3 pounds to 50 
gallons was comparatively effective, although far from satisfactory. 
There were some dead beetles on the ground, and 40 per cent of those 
in the bag were dead. There was a good deal of feeding on the tree. 
The sweetened arsenate of lead applied at the rate of 5 pounds to 
50 gallons was effective. There were many dead beetles on the ground 
under the trees, and of the beetles in the bag 96 per cent were dead 
when examination was made three days after spraying. The trees 
sprayed with this mixture were effectively protected from injury. 
On June 14 a tree that had been sprayed with 2 pounds of arsenate 
of lead to 50 gallons three days previous was resprayed with the same 
mixture to test the effectiveness of a double spray with a weak solu- 
tion. The application was ineffective. 
A second comparison of the sweetened and unsweetened mixtures 
of arsenate of lead was made June 19. The only strength of poison 
used was 5 pounds to 50 gallons of water, the weakest solution 
