THE PEA APHIS WITH RELATION TO EOEAGE CROPS. 3 



pisi. More recently has come a contribution from Prof. Fred. V. 

 Theobald (11, 12) who considers gei and ulmariae as distinct species, 

 thus corroborating the general conclusions of the two eminent Rus- 

 sian entomologists, Cholodkovsky and Mordwilko. Theobald sepa- 

 rates these large green pm-like Macrosiphums into two groups ac- 

 cording to the structure of the tip of the cornicle: (1) Those with the 

 tip imbricated, containing pisi Kalt., loti Theob., and trifolii Theob., 

 and (2) the group of closely related species with the tip of the cor- 

 nicle reticulated, including ulmariae Schr., gei Koch, and stellariae 

 Schr. Further, he is of the opinion that ononis Koch is distinct 

 from pisi. Our own studies lead us to follow Mordwilko's conclu- 

 sions. Schrank's description of Aphis ulmariae certainly seems to 

 indicate that he was dealing with a true Aphis and not a Macrosiphum. 



In 1782 Moses Harris, in his "English Insects, " (1), figures an aphis 

 which he calls Aphis pisum and gives a nondescript description. 

 Theobald (12) has placed this species as a synonym of pisi, but there is 

 nothing excepting the specific name to link it with the aphidid under 

 discussion and it must therefore be placed as a possible synonym of 

 pisi but not in the sense of having priority. 



In 1841 Sir Oswald Mosley (4) describes Aphis lathyri as follows: 



8th Species: Aphis lathyri. — On the Sweet Pea beneath the leaves; colour green, 

 becoming when old of a dark purple; antennae longer than the body; abdomen 

 acuminated, with tubercles nearly extending to the extremity. 



There is little doubt but that this description referred to pisi, but 

 even with two years' priority the name lathyri can hardly take pre- 

 cedence over the well-established name pisi and must be placed in 

 the same category as Harris's pisum. 



The correct name which should be adopted for this insect is still 

 somewhat questionable, but at this distance we, in America, must 

 follow largely the researches of European aphidologists. M. pisi 

 Kalt. must for the present be considered as having priority, although 

 further researches may prove Aphis onobrychis B. de Fonsc. to be 

 identical, this species having two years' priority over pisi, as stated 

 above. In this connection Mordwilko (10) says: 



The same species of plant louse [referring to pisi] was apparently described two 

 years earlier (1841) by Boyer de Fonscolombe and named Aphis onobrychis, having 

 been found on Hedysarum onobrychis. However, it is still premature to regard these 

 two names as synonyms. 



Walker, Buckton, Ferrari, Schouteden, Theobald, and others have 

 made onobrychis a synonym of pisi but none has given sufficient evi- 

 dence to support this conclusion. Authors discussing a plant louse 

 on pea under the name ulmariae doubtless had in mind M. pisi, 

 since it seems to have been fully proven that the true ulmariae does 

 not feed on the hosts recorded for pisi. Further, we must accept 



