184 



FOREST ENTOMOLOGY. 



PONTANIA ISCHNOCERUS (ThotU.) 



Nematus ischnocerus, Th. 



I have only found this species at Kielder, Northumberland. 

 Cameron gives three localities viz., Bannoch, Braemar, and New- 

 Galloway. Fig. 172 is a rep- 

 resentation of the galls on the 

 leaves of a species of Salix. 

 This species cannot in any way 

 be considered as an important 

 forest insect, except in so far as 

 it is of interest in a collection. 



Genus Pteroxus. 



Fig. 172. Galls o/Pontania ischnocerus on 

 species of Salix. 



This genus contains a number 

 of species which have been 

 selected from the old genus Nematus, as regards structure and life- 

 history peculiarities. Perhaps the best plan for the student to 



master the same from a typical species is 

 to work out the life-history of the goose- 

 berry saw-fly, P. ribesii, Scop., hitherto 

 known as Nematus ribesii. For specific 

 characters the systematic student is advised 

 to refer to the " Synoptic Table of British 

 Pteronus," by Eev. F. I). Morice, in the 

 ' Entomologist's Monthly Magazine ' for 

 June 1906. 



Pteroxus salicis (Linn.) 



1 It often happens that in our early 



/ summer or late autumn rambles we find 



*?*' bushes of Salix caprece defoliated by saw- 



fly larvae, as in fig. 173. In this case the 

 insects proved to be P. salicis, as identified 

 by Eev. F. D. Morice. 

 The perfect insect has black antennae, black or dark-brown stigma, 

 and in both sexes a bright orange-coloured abdomen. 



The insect is double-brooded, and can be very easily hatched out. 



Fig. 173. Leaf of goat willow 

 (Salix capres) eaten by larvw 

 o/Pontania salicis. 



