CATALOGUE OF BRITISH PLANT-GALLS 143 



one within the other, thickened and more or less deformedi 

 brown. The fusiform cavity contains numerous reddish 

 larvae (20 to 30). The gall dries up after the departure 

 of the larva or imago. M. G. or M. E. (Plate VIII. 4.) 



Perrisia terminalis H. Low 92 



Syn. Dasyneura terminalis H. Low, Cecidomyia termin- 

 alis H. Low. 



Connold, Plant Galls, p. 246. Houard, No. 582. 



Diptera Leaf margin tightly rolled towards the lower surface, 

 tinted yellow or reddish, roll 3 mm. long. Numerous 

 galls are usually present, and the margin is often rolled 

 continuously for the greater part of its length on both 

 edges of the leaf. M. G. I. 



Perrisia marginemtorquens Winn. 93 

 Syn. Dasyneura marginemttirquens Bremi. 

 MacDougall, Gall-Gnats on Osiers and Willows, Jour. 

 Bd. Agric, Oct., 1905. Houard, No. 590. 



Hypertrophy of woody tissue on branches up to 4 inches 

 in diameter, causing an irregular an d slight swelling. These 

 . galls usually occur in large numbers on one branch, 

 causing an elongated fusiform swelling ; the bark on its 

 surface cracks and falls away. Larva greenish-yellow. 

 M, G. Imago appearing the following May or June, 

 leaving by a minute circular hole. 



Rhabdophaga saligiperda Dufour 94 



Syn. Cecidomyia saliciperda Dufour. 



R. Stewart MacDougall, Gall-Gnats on Osiers, Journ. 

 Bd. Agric, Oct., 1905. Houard, No. 585. 



,, Fusiform or spherical plurilocular swelling up to 10 mm. 



in diameter on one-year twigs, caused by hypertrophy of 

 the woody tissue. Surface pitted and of cork-like consis- 

 tency. Petiole and midrib of the leaf also swollen ; gall 

 ovoid, hard, unilocular, yellowish-green, sometimes tinted 

 with red. Larva whitish at first, then reddish. M. G., 

 just below the outer skin. The pupa has a notch at the 

 base of each antenna sheath. Imago appears late in May. 



Rhabdophaga salicis Schrank 95 

 Syn. Cecidomyia salicis Schrank. 

 Connold, Plant Galls, fig. 314. Houard, No. 587. 



Salix alba Linn. 92. White Willow. 

 Hymen- Bean-like swellings on the leaf blade. See No. 90. 

 optera Cameron observes that "on Salix alba the galls , are 

 usually pale green, rarely light red, and hairy below." 



Pontania proxima Lepel 96 

 Syn. Nematus gallicola Ste. 

 Cameron, ii., p. 203. Houard, No. 633. 



