.nn f November, 



LoJi 



to see some of my captives acquiring wing-cases, and shortly after 

 becoming winged, and showing the character of the genus Pemphigus, 

 Hartig. 



Therefore, these under-ground lice pass from this day from the 

 genus Bhizohius to Pemphigus, as the winged form is no longer un- 

 known, and we ought to say, Pemphigus menthcs and P. sonchi. 



But this is not all ; the very same day in which I obtained in my 

 study these winged forms, my strips of paper on the trees furnished 

 me w^ith the same lice in liberty, the first on the elm, the second on 

 the poplar. 



As regards the elm, little doubt is possible, there is only one 

 Pemphigus on that tree, described already by Haliday, under the name 

 oi Eriosoma pallida, some fifty years ago (1838), and the Pemphigus 

 of the mint-roots is exactly similar to the example taken the same 

 day on the elm. I think Phizohius menthce must disappear altogether, 

 as it is the under-ground stage of Pemphigus pallidus,* of which the 

 whole history is now known. 



Just the same is to be said of Phiz ohius sonchi, w^hich is the under- 

 ground form of Pemphigus hm^sarius, a Linnean name, which has, of 

 course, the priority. Yet this second fact is not so sure as for the 

 elm gall-louse, as there are to my knowledge 20 to 25 different species 

 of Pemphigus on the poplar (in Europe and America). But I think, 

 by the markings of the antennae, it is hursarius, easy to distinguish 

 from all others by its gall fixed on the stem. The only one w^hich does 

 not fall in winter, but remains on the tree. 



I must add, for those who, like Prof. Rudow, describe the gall- 

 lice found late in the season in the gall as the authors of the swelling, 

 that there is a great chance of error in that proceeding. The lasting 

 gall of Pern, hursarius is very often adopted by all winged gall-lice of 

 the pupiferous stage, as a convenient winter dwelling for depositing 

 their sexuated proles, w^hich pair in the gall and conceal their eggs in 

 the same ; so that now, in the first days of October, for an example or 

 two of the true Pern, hursarius, there are hundreds of P. spirothec(ie,\ :^^^ 

 P. affinis, P. pyriformis, P. marsupialis, P. populi, &c. Even true 

 Aphides are not uncommon in these galls, and Chaitophorus populi 

 mixes often with the Pemphigi, in order to deposit its eggs in the 

 same galls. 



In conclusion, Bhizohius menthce and Bh. sonchi must be placed 

 as synonymous to Pemphigus pallidus and Pemphigus hursarius as 

 under-ground forms of the same. 



Montpellier : October 6th, 1884. 



* The genus Eriosoma was not adopted on the Continent, where the Hartigian names pre- 

 vailed, and even Buckton, in his "British Aphides," gives Eriosoma only as a synoymn. 



