SOME PLANT-LICE AFFECTING PEAS, CLOVER AND LETTUCE

Extract

Nectarophora lactucœ, Walk.

(Pl. III., 8.) Several writers have listed S. lactucœ, Kalt as an American species. That of Thomas is noted below. Dr. J. B. Smith gives the species in his Insects of New Jersey. Whether the species occurs in this country or not is open to question. It should be noted here that Kaltenbach's Aphis lactucœ is a Rhopalosiphum. Buckton gives both Siphonophora lactucœ, Kalt. and Rh. lactucœ, Kalt., though Kaltenbach described but one species. Walker (Ann. and Mag. Nat. Hist., Ser. 2, p. 49, 1849) in his description of the species confused it with Rh. lactucœ, Kalt., as Passerini has pointed out. Walker described it as Aphis lactucœ, Linn. and as a synonym of A. lactucœ, Kalt., though Kaltenbach had already shown A. lactucœ, Linn. to have been invalid, and that his species was entirely distinct. Walker also gives A. ribis-nigri, Mosley (Gard. Chron. I., 684) as a synonym. Mosley's description is hardly recognizable, but evidently is the same as some of the varieties described by Walker, both undoubtedly referring to Rhopalosiphum ribis, Linn., and Myzus ribis. Unfortunately, Walker describes only the coloration of his species. Part of his species is evidently, however, N. lactucœ. Passerini's description is too brief to be recognizable, but probably refers to the same species, as Buckton thought. Why Buckton described the species as S. lactucœ, Kalt., is not clear. Buckton follows Walker in giving Ribes nigrum and grossularia as food-plants, and remarks that Walker states that the cornicles are enlarged at the middle, but does not otherwise seem to confuse the species with others as did Walker.