IXSECTS INJURIOUS TO THE SUGAR-BEET. 255 



The Beet-aphis (Pem^jhigus letce Doane). 



This species was first described by Mr. W. R. Doane in 

 1900 and seems thus far to have been found only in 

 Washington and Oregon. "^Attention was first called to 

 this pest/^ he says,* "in 1896, when it was found that a 

 field of two or three acres of beets was generally infested, 

 a strip of twenty-five to a hundred yards being so badly 

 injured that the beets were nearly all soft and spongy, and 

 the plants much smaller than the averiige. f 



' ' It has been even more destructive in Oregon than in 

 Washington, at least a thousand tons of beets having been 

 destroyed by it in one year in a single valley devoted 

 largely to beet-culture. Like very many other beet-insects, 

 this species infests also several wild or useless plants. 



"The smaller rootlets of the beet are first attacked by 

 this aphis, and if it occurs in considerable numbers these 

 are soon all destroyed, and the leaves thereupon soon 

 wither, and the whole beet shrivels and becomes spongy. 

 This wilting of the leaves will frequently, in fact, be the 

 first thing to attract the attention of the beet-grower. 

 The actual injury to the crop will, of course, depend 

 largely upon the time when the attack of the aphis is 

 made. If the plants are small they may be readily 

 destroyed, while if they are practically full-grown the loss 

 of the small rootlets will not materially affect them. 



* ^ No sexual generation of this aphis has as yet been dis- 

 covered and no eggs have been seen, viviparous reproduc- 

 tion continuing throughout the year except when the cold 



* Bull. No. 42, Wash. Agr. Exp. Sta. 



t Forbes and Hart, Bull. Xo. 60, Univ. 111. Agr. Exp. Sta., 

 p. 507. 



