138 MANUAL OF VEGETABLE-GARDEN INSECTS 



bisiilfid is used, the liquid is placed in a shallow dish under the 

 cover and allowed to evaporate. About a teaspoonful is suffi- 

 cient for one cubic foot of space." The cover should be made to 

 fit tightly to the ground to prevent the escape of the gas. The 

 fumigation method is of most value when only a small number 

 of vines are to be treated and when the aphids make their 

 appearance before the vines have begun to run so as to cover 

 much space. In large fields, spraying is more practicable and 

 more likely to give . satisfactory results. For successful spray- 

 ing it is necessary that the vines be trained to run in the rows ; 

 this also makes the cultivation easier. When the vines are 

 trained in this way, it is not difficult to kill nearly all the 

 aphids by using "Black Leaf 40" tobacco extract, f pint in 

 100 gallons of water in which 5 or 6 pounds of soap have been 

 dissolved. The spraying should be done as soon as the lice 

 appear. A fine nozzle should be used, which, with good pres- 

 sure, will produce a fine mist. It is important that the spray 

 hit the underside of the leaves. This can be accomplished by 

 using an upturned angle nt^zzle on a short extension rod. By 

 doing careful and thorough work, it is possible to hit the under- 

 side of practically every leaf. In case the infestation has be- 

 come severe, it may sometimes be advisable to use a stronger 

 solution of the tobacco extract, 1 pint of "Black Leaf 40" to 

 100 gallons of water. Much stronger mixtures will not injure 

 the foliage but are unnecessary and rather expensive. This 

 method of fighting the melon aphis has proved practicable 

 under commercial conditions. 



References 



Pergande, Insect Life, VTI, pp. 309-315. 1895. 

 Tex. A^\ Exp. Sta. Bull. 89, ])p. 43-46. 1906. 

 U. S. Bur. Ent. Cire. 80. 1906. 

 Okla. A^\ Exp. Sta. Bull. 98. 1912. 

 III. Agr. Exp. Sta. Bull. 174. 1914. 



