28 



be secured, since trap cages used on areas so treated yielded no beetles, 

 but possible injury to the trees which might result, still renders the 

 method of doubtful economy. 



Poisoned bran mash. — Since the beetles sometimes leave hiberna- 

 tion before the apple trees are in leaf it was thought that a poisoned 

 bait scattered on the grass under the trees might attract the beetles and 

 destroy them. The standard grasshopper formula was used — bran, 20 . 

 lbs.; Paris green, 1 lb.; syrup, 2 quarts; 3 grated lemons; and Syi gal- 

 lons of water. Two and a half lbs. of the bait was scattered under the 

 spread of 35-year old apple trees on April 27, when the beetles were be- 

 coming active and the foliage was just starting. Not only did the bait 

 fail to attract the beetles in the open, but individuals confined with it 

 did not die from eating it. 



Spraying the trash under the trees zuith a solution of potassium ferro- 

 cyanidc. — In early April, before the beetles became active, the grass and 

 mulch under apple trees in a badly infested orchard was evenly sprayed 

 with enough of a solution of potassium ferrocyanide to make the mulch 

 quite damp. Two strengths of the solution were tried; one of a pound 

 and another of 2^ pounds to 50 gallons of water. It was thought that 

 the fumes might kill the hibernating beetles, but no dead beetles were 

 found in the treated areas, and later on, when the beetles emerged, these 

 trees were as severely attacked as their untreated neighbors. 



Spraying the trash 7vith other materials. — ^In 1919, an orchard at 

 Flora, Illinois, heavily infested with weevils, was selected for a series of 

 experiments to ascertain if wetting the refuse beneath the trees with a 

 contact insecticide would destroy the beetles in hibernation. The orchard 

 had been cultivated down the center of the space between the rows but 

 not within six or eight feet of the trunks of the trees. The litter under 

 the trees was of about the usual depth. During the latter part of No- 

 vember plots were laid out six trees square and the litter under the 

 trees was sprayed with enough of the insecticides to wet thoroughly 

 through the cover to the surface of the soil. The amount applied was 

 15 gallons per tree. 



Before the insecticides were applied, counts were made of the num- 

 bers of flea-weevils in hibernation about the bases of a number of trees 

 in each plot. The weevils were also counted imder five trees left un- 

 treated as a check. During the latter part of February another series 

 of counts was made on the same number of trees in the center of each 

 plot and the number of living and dead weevils was noted. The results 

 of these treatments are given in the following table. 



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