84 JOURNAL OF ECONOMIC ENTOMOLOGY [Vol. 15 



aphis. It has made a strong appeal to leading cabbage growers in 

 this area who heretofore have been very lukewarm towards spraying as 

 a method of combating the aphis. In the immediate vicinity of the 

 experiments it has been estimated that dusting materials to the value of 

 approximately S8,000.00 were applied to cabbages. 



For the control of cabbage aphis and cabbage worms we prefer, for 

 the present, the formula which provides for 5 pounds nicotine sulfate, 

 15 pounds of powdered lead arsenate or calcium arsenate, and 80 pounds 

 of hydrated lime. If the caterpillars are not very numerous, it is 

 believed that the arsenical may safely be reduced to 10 pounds. 



The Potato Aphis 



Of the various insects considered in our experiments, the potato 

 aphis (Macrosiphum solanijolii Ashmead) was the most difficult species 

 to combat satisfactorily. It is apparently not as susceptible as the 

 foregoing forms to common insecticides, and the dense foliage and 

 matting of the vines constitute formidable obstacles to effective treat- 

 ment which can only be overcome by painstaking work. 



On the basis of the insects infesting the tips of the growing shoots, 

 dehydrated copper-lead arsenate, containing 2 per cent nicotine, killed 

 52.3 per cent of the aphids at a dosage of 50 pounds per acre, and 83.2 

 per cent at a dosage of 90 pounds per acre. Nicotine and soap, using 

 100 gallons per acre destroyed 85.5 per cent of the aphids. 



Notwithstanding the fact that many insects in some of the plats 

 escaped, it should be noted that all the applications checked appreciably 

 the rapid development of the aphids on the growing tips of the vines, 

 which seemed to afford noticeable protection to the leaves. The plats 

 that were left untreated displayed much discolored, withered foliage 

 as the result of the uninterrupted feeding and breeding of the aphids. 

 And one unacquainted with the plans of the tests had little difficulty in 

 distinguishing the untreated plats from the treated plats. 



Conclusions 



In view of the data obtained from the foregoing experiments it is 

 concluded that apple red bugs and certain aphids may be effectively 

 controlled by thoro dusting with sulfur-lead arsenate or calcium hydrate 

 containing nicotine sulfate. The outstanding advantage of dusting 

 is speed of operation which effects noticeable economies in time and labor. 

 A serious drawback is the high cost of the preparations, due chiefly to 

 the large amount of nicotine required to make effective mixtures. 

 Notwithstanding the economy in time and labor, dusting on the basis 

 of existing prices for materials and labor has generally been more ex- 

 pensive than spraying, except possibly in the treatment of cabbages. 



