THE PEA APHIS WITH RELATION TO FORAGE CROPS. 11 



Mr. D. T. Fullaway (1910) reports having taken M. trifolii Perg. 

 (=pisi) on Sonchus oleraceus in Hawaii, but an examination of the 

 specimens through the kindness of Mr. Fullaway shows them to be 

 something other than pisi. We have also had the privilege of 

 examining the specimens collected and recorded by Mr. W. M. 

 Davidson (1909) as M. pisi on Urtica Tiolosericea, and they prove to 

 be of another species. 



We have a number of individual office records reporting M. pisi 

 on alfalfa. Among these, specimens for which were examined by 

 the writer, are the following: Mr. C. N. Ainslie collected it on this 

 host at Prairie Grove, Ark., March 21, 1907, all stages being found. 

 An examination of this material shows a mixture of II. pisi and M. 

 creelii, although the former species predominates. Mr. Ainslie also 

 collected this aphidid at Arlington, Va., April 6, 1908, on alfalfa. 

 Mr. V. L. Wildermuth collected it on alfalfa at Holtville, Cal., April 

 17, 1912, and at Muirkirk, Md., April 28, 1909. At the latter place 

 the infested alfalfa had a wilted appearance, and because of their 

 abundance this injury was supposed to be caused by the plant-lice. 

 Probably the most noteworthy example of pisi occurring on alfalfa 

 was recorded by Mr. J. A. Hyslop, who, on November 12, 1912, 

 observed these aphides swarming in an alfalfa field near Funkstown, 

 Md. At this time very few viviparous forms were observed; the 

 males and oviparous females predominated, and a few days later 

 the black shiny eggs were found abundant on the alfalfa leaves. In 

 this same field Mr. Hyslop observed the aphides abundant in May 

 (1913), but in August not a single individual was found. Further 

 observations were made in this field by Mr. C. M. Packard in October 

 (1913), at which time the aphides were again abundant. Mr. J. T. 

 Monell has determined as this species plant-lice collected on alfalfa 

 at Wellington, Kans., May 4 to July 30, 1909, by Mr. E. O. G. Kelly. 

 In all cases where this aphidid occurred on alfalfa it was found on 

 the young terminal buds and leaves. 



The following is a list of the authentic hosts of M. pisi as recorded 

 in America. Although shepherd 's-purse is retained as a host of this 

 plant-louse, we have never seen specimens of this species collected 

 on that plant. Shepherd' s-purse {Bursa bursa-pastoris) , lentil 

 (Ervum sp.), sweet pea (Latliyrus odoratus), grass pea (L. sativus), 

 alfalfa (Medicago sativa), white sweet clover {Melilotus alba), 

 garden pea and field pea (Pisum sativum) , crimson clover ( Trifolium 

 incarnatum) , red clover (T. pratense), white clover (T. repens), 

 vetches or tares ( Vicia ludoviciana, V. gigantea, V. villosa, et al.) . 



The following reliable hosts have been recorded by European 

 writers. Many of the recorded hosts, such as Geum, Ulmaria, etc., 

 are certainly incorrect, while others are highly improbable, and as 

 they have not been corroborated since the correct identity of pisi 

 has been understood, they are not here included: Shepherd' s-purse 



