Galls caused by the queen and nymphs of Pemphigus 

 bursarius Koch. 



on 



the petioles of leaves of Populus nigra Linn. 



PLATE 10 J,. 

 Synonymy of Insect. 



Apliis bursaria Linn., Fab., Sch., Kirby and Spence. 



Eriosovta populi Rennie, Mosley. 



Aphioides bursaria Rondani. 



Pemphigus bursai-ius Kalt., Htg., Pass., Kerner. 



Habitat of the Black Poplar.— Common in most parts 

 of Britain in woods, gardens, and parks, along the banks 

 of rivers and streams and other moist places. 



The Gall is formed by the queen aphis puncturing the 

 petiole of the leaf; the edges of the swelling thus caused 

 arise and surround her. 



Position. — On the petiole of the leaf; occasionally on the 

 mid-rib. 



Manner of Growth. — Singly ; pear-shaped or oval purse- 

 like swellings. 



Colour. — Same tint of green as the petiole, frequently suffused 

 with pink. 



Average Dimensions of a Mature Specimen. 



Length, 15 mm.; breadth, 10 mm.; girth, 30 mm. 



May be sought during the months of July, August, September. 



The Growth is complete by the end of August. 



The Typical Condition of the gall is multinymphal. 



ECDYSIS takes place in the gall. The imagines emerge during 

 August. 



The gall is also figured by J. Rennie, " Insect Architecture," 

 1845, vol. ii., p. 135; Buckton, "British Aphides," vol. iii., 

 plate 3, p. 113; A. Kerner, "Nat. Hist, of Plants," vol. ii., 

 P- 534- 



239 



