HYMENOPTERA SAW-FLIES, ETC. 



189 



cannot give any description. It would be well, therefore, for the 

 student to work it out, more especially as it is not mentioned by 

 Cameron except as a synonym; and the assumption that the above- 

 named insect is the one responsible for the damage on spruce is 

 based on the description given by German writers, together with 

 correspondence from Mr Morice. 



SIRICID^E (Wood-wasps). 



As regards forest insects, this family is represented by the genus 

 Sirex. The injuries are chiefly done by the larvae to back -going 

 standing trees, and timber of a secondary class is therefore further 

 depreciated by the larval borings. 

 The trees which are attacked 

 are Scots pine, silver fir, spruce 

 fir, and larch. 



The genus Sirex is represented 

 in this country by two species 1 

 viz., Sirex gigas, Linn., and S. 

 juvencus, Linn. There are three 

 species in Germany \'\z.,S. juv- 

 encus, S. gigas, and S. spectrum. 



Sirex gigas, Linn. 



This fine insect often attracts 

 considerable attention in estate 

 timber-yards, where lo<?s of Scots Fi s- ^o.-Plank ofsUnrfir (Abies pectinate) 



J injured by Sirex gigas. 



pine, spruce, silver fir, and larch 



are cut up, more especially where the cut logs have been either lying 

 for some time in the yard, or where sickly or previously blown trees 

 (which were unfit for sale) have been brought to the sawmill yard. 



This insect is credited with being a very destructive species, but 

 this appears to be an exaggeration, inasmuch as it always attacks 

 sickly timber. Fig. 180 is from a photograph of injuries done to a 

 plank of silver fir (Abies pectinata). 



1 There is a third species viz., S. noctilio but it is very difficult for the 

 practical man to distinguish it from S. juvencus. All three occur in England, 

 but systematic men consider that juvencus is evidently far rarer than 

 noctilio. 



