ANNUAL REPORT, 1939 35 



Length to wing tips, about eleven sixteenths of an inch. Wing expanse, nearly 

 an inch and a quarter. Head mostly medium brown. Thorax mostly medium 

 brown dorsally but with a whitish collar in front margined behind with black. 

 Thorax below and legs light to dark gray. Abdomen mostly gray or smoky 

 brown, with much pale yellow at the tip on the males. Forewings variegated 

 above with gray and medium brown, with a narrow streak of black running 

 out from the base and touches of black near the middle and toward the outer 

 margin, and with a very irregular pale yellow or whitish line running across the 

 outer end a little back from the border. Hindwings smoky above, gradually 

 lighter toward the base. Underside of wings grayish brown of varying shade, 

 that of the hind pair whitish toward the base of the hind side and with a darker 

 dot near the center. 



Gypsy Moth {Porthetria dispar). Numerous applications of various derris 

 dusts (with and without activators and wetters), up to 100 pounds an acre of 

 4 percent rotenone derris (without activator) and of derris dusts with moderate 

 admixtures of pyrethrum powder failed to give satisfactory kills of the largely 

 grown caterpillars of this pest. Dusting to control them in any way with rotenone 

 materials seems entirely impracticable. 



Cravherry Root Grub {Amphicoma vulpina). Studies of the life history of 

 this pest in recent years have shown that the grubs remain in the soil four or 

 five years depending on their luck in obtaining food. Due to this variation, 

 grubs hatched in several different years often come to be associated in the soil. 



The cyanide treatment, used extensivel}' for this pest with more or less success 

 for several years, is somewhat dangerous when applied carelessly, sometimes 

 fails to be effective enough, and takes too much time. A more satisfactory 

 insecticide control is therefore much desired. For this reason, the following 

 treatments were tried on infested plots late in April: 



1. Sodium fluoride up to a pound in 50 gallons of water, applied a gallon 

 to a square foot. 



2. Semi-colloidal arsenate of lead up to 12 ounces in 50 gallons of water, 

 applied half a gallon to a square foot. 



3. Sodium arsenite up to half a pound in 50 gallons of water, applied a gallon 

 to a square foot. 



4. Sodium fluoride up to 1000 pounds an acre, applied as a dust. 



The plots were examined late in August and it was found that none of the 

 sodium fluoride or arsenate of lead treatments had reduced the grubs materially. 

 The vines on the areas dusted with sodium fluoride were badly injured and most 

 of the water applications of this chemical had the same effect. Most of the 

 vines and 75 percent of the grubs on the plot treated with 6 ounces of sodium 

 arsenite in 50 gallons of water and all the vines and all the grubs on the plot 

 treated with half a pound in 50 gallons were killed. 



On October 13, a pint of dichlorethyl ether in 50 gallons of water was applied 

 to different infested plots at rates of 1, 2, and 4 quarts to a square foot. These 

 plots were examined November 20; the odor of the chemical was still strong 

 in the soil of all of them and the conditions of the grubs were as follows: 



1. Treated with 1 quart to a square foot — 20 alive, 12 dead 



2. Treated with 2 quarts to a square foot — 31 alive, id) dead 



3. Treated with 4 quarts to a square foot — alive, 31 dead 

 The cranberry vines on the last plot weie badly injured. 



Cranberry Fruit Worm {Mineola vaccinii). The season's experience in con- 

 trolling this pest with rotenone-bearing sprays and dusts, in both experimental 

 work and commercial practice, was in complete accord with that of previous years. 

 A pound and a half of soap in the spray mixture, however, was found enough. 



