EXPERIMENT STATION WORK WITH INSECTICIDES. 271 



favorable for hibernation of the pest and in order to destroy, as far as 

 possible, the hibernating adult insects. If chinch bugs are observed 

 in gi'eat numbers on weeds in stubble after the wheat is cut, large 

 numbers of them may be destroyed by plowing innnediately after 

 harvesting. In order to prevent the march of chinch l)ugs into corn- 

 fields it has been found somewhat efficacious to allow succulent weeds 

 to grow in one or two of the outer rows of the cornfield. Better 

 protection is secured by j)lanting a narrow strip of millet around the 

 cornfield at a time so that it will be from 8 to 10 inches high when 

 the wheat is cut and when the chinch bugs are migrating to the corn- 

 field. If, in the system of rotation adopted on a given farm, wheat is 

 to follow corn, it is desirable that the corn stubble be plowed under 

 and that corn shocks be removed from the field in the fall. In gen- 

 eral wheat and corn should not be planted in close juxtaposition if 

 chinch bugs prevail seriously. In Missouri " the chinch bug is said to 

 cause the most serious trouble when it migrates from wheat to corn. 

 If the chinch bugs migrate in large numbers, crawling in one direc- 

 tion, the army of bugs may be checked by plowing a belt of ground 

 10 feet wide around the cornfield. After plowing, the soil should be 

 harrowed and rolled so as to be finely pulverized. Troughs may then 

 be run likewise through this plowed belt and holes dug at intervals at 

 the bottom of the troughs. The chinch bugs in attempting to cross 

 the troughs will fall into the holes, where they will be covered by the 

 kerosene or tar and will be buried. If such precautions are not tsiken 

 chinch bugs may be destroyed while migi'ating by spraying with kero- 

 sene emulsion or some other contact insecticide. 



THE GREENHOUSE WHITE FLY. 



The white fly of gi-eenhouses, or greenhouse aleurodes {Aleurodes 

 vaporariorum) ^ has long been recognized as a serious pest of green- 

 house crops. In Connecticut^ the pest has been exceedingly injuri- 

 ous to tomatoes and cucumbers under glass. Fumigating with to- 

 bacco was found not to be an effective remedy. Ilydrocyanic-acid 

 gas, when used at the rate of 2i ounces potassium cyanid per each 

 1,000 cubic feet of space, killed the insects but also injured tomato 

 plants. A cheap and effective remedy was found in spraying the 

 under surfaces of the leaves with common laundry soap dissolved 

 in water at the rate of 1 pound in 8 gallons of water. In order 

 to prevent all injury from soap it should be washed from the 

 leaves occasionally with water, with frequent applications of the 

 insecticide when necessary. At the Maine Station'" fumigation with 

 hvdrocvanic-acid gas was the most successful remedv tried. AVhen 



o .Missouri Sta. Bui. 51. & Connecticut State Sta. Bui. 140. 



Maine Sta. Bui. 96, 



