56 MASS. EXPERIMENT STATION BULLETIN 347 



and nicotine sprays, all leafhoppers were killed in 24 hours. When the leaves were 

 dusted with pyrethrum before the hoppers were confined, all of the insects were 

 also killed in 24 hours. Experiments with these materials at constant tempera- 

 tures of 60°, 70°, and 80° F. showed a slight but not consistent increase in effective- 

 ness at 80°. 



Slimmer Sprays for European Red Mite. Laboratory and orchard trials, in 

 eastern Massachusetts, of some of the newer insecticides, especially those which 

 might control both the white apple leaf hopper and the European red mite, 

 indicated that the nicotine and pyrethrum materials were ineffective against the 

 red mite, but that the cyclohexylamine derivative gave good control at dilutions 

 of 1-400 and 1-200. 



Control of the Squash Vine Borer. The average field infestation by the squash 

 vine borer in Hubbard squash at Waltham in 1937 was 3.68 borers per vine, 

 which is three times as heavy as last year. The borer moths were late in appearing 

 and the first treatment was not applied until July 9, followed by 3 additional 

 applications at weekly intervals. 



The liquid sprays were consistently superior to the dusts although the 

 cube-clay dust containing 0.6 percent rotenone was nearly as effective. As in 

 other years, the spray consisting of nicotine sulfate 1-500 plus summer oil emulsion 

 1-100 was the most effective treatment and reduced the borer injur}- 88.59 percent. 

 The wettable cube spray using 4 pounds in 100 gallons of water showed a reduc- 

 tion of 81.53 percent, and being less expensive would seem more practical. Con- 

 trary to the results in 1936, the pyrethrum-clay dust containing 30 percent 

 pyrethrum powder was ineffective. 



Treatment Number Average Percentage 



of Number of Reduction 



Plants Borer Tunnels over the 



per Vine Check 



Check 25 3 . 68 



Nicotine sulfate 1-500 + Oil emulsion 1-100 19 0.42 88.59 



Wettable cube spray, 4 lb. in 100 28 0.68 81.53 



Nicotine sulfate 1-250 22 0.77 79.08 



Cube — clay dust, 0.6 percent rotenone. . 25 0.84 77.81 



*Derris — clay dust, 0.6 percent rotenone 27 1.48 59.79 

 Pyrethrum — clay dust, 30 percent 



pyrethrum 29 2.06 44.03 



*1936 Derris powder; others, 1937 powders. 



Control of Striped Cucumber Beetle on Melons. Striped cucumber beetles were 

 normally abundant in 1937 and killed or damaged seedling melons, cucumbers, 

 and squash which were unprotected. On cantaloupes at Waltham, a part of which 

 were transplanted and a part seeded on June 7, it was necessary to apply insecti- 

 cides 5 times beginning June 10 and ending July 10. Although these applications 

 were made at approximately weekly intervals, no definite period for treatments 

 could be determined and the plants were sprayed and dusted whenever the 

 abundance of the beetles warranted it. During this period several of the untreated 

 seedlings were killed. 



The effectiveness of the field treatments was determined by counts of the 

 number of beetles present on the plants at different periods. A spray of wettable 

 cube powder containing 3.65 percent rotenone and used at the rate of 4 pounds 

 in 100 gallons of water reduced the number of beetles 90 percent, compared to the 

 untreated plants, and was the most effective treatment. Cube-clay dust containing 



