20 'BULLETiisr 352, u. s. departmej^t of ageicultuee. 



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 or 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 arseur 

 ate of lead on June 11. Two, 3, 4, 5, and 6 pounds were used to 50 

 gallons of water; one-haK pound of lime 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 ine£Fective in 

 kiUmg 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 imsweetened 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 



