84 JOURNAL OF ECONOMIC ENTOMOLOGY t^ol. 1 



occur in nearly all portions of the United States where peaches are 



grown. i. 4- •<- V, 



Our interest is also increased when we realize to what extent it has 

 probably been confused with other species of the sub-family Aphididae, 

 and when we understand the factors which have led to this confusion. 

 My first notice of the insect as an economic pest in Colorado was at 

 Grand Junction on April 13th, 1906, and brief mention was made of 

 it in Bulletin No. 119, Colorado Agricultural Experiment Station. 

 Its identity was then unknown to me and before undertaking any con- 

 trol experiments material was sent to Prof. C. P. Gillette, our best 

 authority on the Aphididse of that section. Samples of the material 

 were also sent to Mr. Theo. Pergande of the United States Department 

 of Agriculture, who gave to the insect the name Rhopalosiphum di- 

 anthi Schrank, as did Professor Gillette on first looking over the ma- 

 terial The latter, after further study of the insect and literature, 

 concluded that the name Myzus persicae Sulzer should be applied to 

 it In this studv of it certain matters of importance regarding the 

 synonomy of the^nsect were brought out and I shall quote from a let- 

 ter of Professor Gillette dated November 7th, 1907 : "Let me change 

 my opinion in regard to what this louse ought to be called. I decided 

 to call it diantha Koch, but our species seems to be the persicae de- 

 scribed by Sulzer in 1761 and which is described and figured by Buck- 

 ton in his work on British Aphidid^, vol. 1, page 173. Buckton's fig- 

 ures correspond remarkably well with the louse that we have been 

 working on here. I also believe that Rhopalosiphum solam Thomas, 

 B dianthi Schrank, and Mtjzus achyrantes Monell are synonyms of 

 this species All of the returned migrants that we have found upon 

 plum, peach and cherry during the fall have had cornicles that were 

 slightly swollen or clavate in form. The first winged forms m the 

 spring that appear on these same trees seem exactly like the fall 

 winged form, except that the cornicles are not at all swollen. I was 

 greatly puzzled over this fact last spring and determined to watch 

 very closelv this fall to determine whether or not the form with 

 swollen cornicles would again appear upon the peach and plum trees. 

 For the past six weeks these migrants with swollen cornicles have been 

 gathering upon these trees and depositing the oviparous form which 

 becomes pink or salmon in color as it grows toward maturity. Since 

 the middle of July we have been taking this louse upon a large va- 

 riety of plants and in all cases we have found the cornicles swollen. 

 This seems to account for the louse being called a Rhopalosiphum when 

 described from the summer and fall form and Myzus when described 

 from the early spring form before it leaves the peach, plum and cherry 



