A!PPLE-EO0T BtlGHT ITS GENERIC NAME. 7 



History, under the name of Eriosoma Pyri. All those Plant lice 

 which were formerly included in Dr. Leach's genus Eriosoma, 

 which have all the veins of the wings simple, and those in the 

 ■disk of the hind pair two in number, now furm the genus Pem- 

 phigus of Hartig (Germar's Zeitsch. vol. iii. p. 366), to which 

 genus it is therefore necessary to refer this insect.* Several of 

 the other species of this genus, as well as the present one, are 

 known to infest the roots of plants. I entertain scarcely a doubt 

 that tliis is the same species which Mr. Walker soon afterwards 

 described, from specimens obtained in Nova Scotia, under the 

 name of Pemphigu Americanus ; though the length which he as- 

 signs to it (four lines) is rather greater than any individuals t 

 have mtt with. 



To our nurserymen it obviously belongs, to fully e-lucidate the 

 history of .this species, and the disease which it occasions, as they 

 enjoy opportunities lor observing it such as belong to no other 

 profession. The knots, or excrescences, occur both upon the large 



• Mr. Westwood, in his Areana Entomologia, vol. ii. p. 63, observes that the name JBryso- 

 'Crypta (Byrsocrypta) of Hiliday must be retained for Hartig's genus Pemphigus. And on 

 the next page we are told: "The generic name of Eriosoma (Leach) must take place of 

 that of Pemphigus,, and be reslricted to such species as diifer from Aphis bursarius," There 

 is a contradiction here, which I can only account for by supposing the distinguished author, 

 who is so accurate a nomenclator, has inadvertently placed the name Pemphigus in the lat- 

 ter quotation, where he intended to insert Schizoueura. The first division of the old Lio- 

 nasan genus Aphis appears to have been made in 1819, when Samouelie (in his Entoraologiat'3 

 'Companion, p. 232) published the genus Eriosoma from Dr. Lfaoh's MSS., with the "■ E, 

 Mali, the Aphis lanigera of authors," or the well-known Apple tret blight, as its type. 

 Samoaelle's little work, truly a " Uf«ful Companion" in its day, probably was not circulated 

 upon the Continent, and entomologitts there seem to have been uninformed of its cuutents* 

 Several synonyms, in consequence, have unfortunately been introtluced into the science, f ive 

 years afterwariis, Blut (in the iVlemoirs of the tinnsean Society of Calvados, vol. i. p. 114) 

 named the same insect JMyzoxijlus Mali, which name has been extensively circulated by 

 French writers. Still more recently, Ilartig (in Sermir's Zuitsohnft, vol. iii. p. 367) baa 

 proposed the name Sohizoneura for this same genm; whilst Macquart has bestowed the name 

 Eriosoma upon a genus of flies, in the Order Dip'era. Mr. Westwool is clearly right in re- 

 taining Dr. Leach's name for the genus having Aphis lanigera as its type. 



With regard to the statement first made above, I would observe, Mr. Haiiday first proposed 

 the genus Bijrsoorypta, if I mistake not, in the Annals of Nut. Hist, for the year 1839, page 

 189, placing under this genus the Aphis Uhni of Geoffrey, and a new speeiis which he names 

 pallida. We hence regard the Vlmi and not the bursarius as the type of .Mr. llaiiday"3 

 genus. Consequently the name Hyrsocrypta must be retained for the genus which has Dlmi 

 for its typo, namely, the Tetraneura of Uartig; whilst his genus Pemphigus, with bursarius 

 «j3 its type, is entitled to stand. I therefore give our Araurican species under this name. 



