182 FOREST ENTOMOLOGY. 



is very common at Kielder, Northumberland. The galls are on the 

 under side of the leaves (fig. 169), and as a rule a single specimen is 

 found on each leaf, though at times two galls coalesce together. 

 They mny be either glabrous or slightly hairy, and as a rule the galls 

 which coalesce generally develop min- 

 iature warts. The colour is greenish- 

 yellow, with small reddish spots, and 

 the average diameter from 6 to 8 mm. 

 It may be looked for from July to 

 yi-' fi' '''^W^i l^^iB September. 



■ ^ ^MtM Each gall contains a single larvge. 



The grub is very active, and the 

 frass is found within the gall. As 

 Fig. i69.-Gn«.«r)/Pontaniasaiipiso(i y^g larvae pupate in the soil, it is 



traces r/Salix capreiv. ^ '■ 



well to gather the galls fairly early 

 for artificial breeding. The flies hatch out about the beginning of 

 ]May (May 9, 1905). 



Female. — Head and thorax black ; antennae dark - brown ; 

 abdomen black, with yellowish bands at division of segments. 



Under side of abdomen yel- 

 low and black. Legs pale, 

 testaceous. Wings hyaline. 

 Stigma dark-fuscous, 



Male. — Colour very much 

 as in female. Smaller in 

 size, and antennae stouter. 



PoNTANiA BELLA (Andre). 



The galls of this species 

 (fig. 170) very much re- 



FiS. 170.— f;f'?^-!r,/Pontaniabellao»Z«acsn/ semblc those of the pIC- 



Salix viminalis. ' 



ceding, except that they are 

 always found on S. viminalis., which is perhaps the most important 

 distinction to the practical man. 



The insects are also very much like those of the previous species ; 

 but they hatch out much later in the season — viz., about the end of 

 June. 



