"steel blue" or " co^nroN " rirex. 259 



The size varies from about half au inch to an inch and a 

 third or an inch and a half in length, and from about three- 

 quarters of an inch to a little above two inches in the spread 

 of the wings. This variation appears to me to be much 

 influenced by the conditions of the maggots having been 

 favourable or otherwise, for amongst specimens sent me 

 during 1889 some fine females, measuring quite the fullest 

 length given above, were sent me from an old Silver Fir, 

 where everything must have been suitable for growth ; whilst 

 amongst specimens from some buried wood used for supporting 

 drain-pipes I had a male just under half an inch long, and a 

 female five-eighths of an inch long, including the ovipositor. 



The habits of these two kinds of Sirex (that is, of the S. 

 juvencHs and S. fjigas) appear to be almost exactly similar. 

 The females pierce into the bark of the Larch, Silver Fir, or 

 other kind of Conifer that they may attack (standing or felled, 

 as the case may be), and with their strong ovipositors deposit 

 their eggs, one at a time, in the soft wood immediately 

 beneath, and in each case the maggots are whitish, soft, and 

 cylindrical, with scaly heads furnished with strong jaws. The 

 three pairs of feet are very small, and at the rounded tail- 

 extremity (above) there is a blunt point or spine ; they feed in 

 the solid timber, causing great injury by their large borings. 



In an estimate sent me in 1889, by Mr. W. Hodgson, 

 A.L.S., of Workington, Cumberland, of loss caused by damage 

 from maggots of Sircx juvencus (of which specimens were 

 identified) to some Silver Fir trees at Gilgarron, near White- 

 haven, he reported as follows : — 



The number of Silver Firs on the grounds is slightly in 

 excess of forty trees, of over seventy years' growth, varying in 

 bulk from twenty to forty cubic feet per tree. This will give 

 on the whole a trifle over 1200 cubic feet of timber irretrievably 

 damaged, which, estimated at sixpence per foot, represents a 

 loss oi £S0 in money value, to say nothing of the injury done 

 to the appearance of the woods and coppices. — (W. H.) 



With regard to prevention of Sirex-attack to old Silver Fir 

 trees, it is possible that something might be done to protect 

 favourite or specimen trees by finding whether from age or 

 other circumstances the outer bark was flaking off in the way 

 described in Selby's 'British Forest Trees,' p. 472, leaving a 

 newly-exposed cuticle. 



Where the thin under-bark is thus exposed, it would 

 presumably be particularly inviting to Sirex-attack, and for a 

 few favourite trees it would be worth while to try the eftect of 

 a good smearing with soft-soap preparation, or any deterrent 

 which would be likely to protect the tree (where the bark had 

 scaled off) during the time when the " Timber Wasps " are 



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