SIREX GIGAS, LINN., IN BUTE AND ARRAN. 189 



I had these pieces of wood under observation all summer, and 

 at the beginning of August the first flies made their appearance 

 from the wood, through circular openings slightly smaller than 

 the ordinary holes bored in the larval stage. 



How long the eggs take to hatch and the insect remains in the 

 larval state I have still to learn. But now that it is known to be 

 a native of some of our woods in the Clydesdale district, data may 

 soon be forthcoming to clear up those points. The places to look 

 for it are where Scotch and Silver Firs srrow in some abundance. 

 I am convinced that if more of our woods in other localities were 

 properly examined the fly would be found in them too. 



Trees which have begun to decay should receive careful atten- 

 tion, as the fly seems to attack them in preference to those which 

 are healthy and growing. The tree from which these pieces 

 containing the larvae were taken was partially dead when it was 

 cut down. But whether the eggs had been deposited while it was 

 still standing, or not until it had been cut down, it is difficult to 

 determine. The larvae do not seem to be able to continue their 

 operations after they have been disturbed or exposed in their 

 borings, but soon shrivel up and die. At least this has been my 

 experience with them, and it prevents observation of their opera- 

 tions, which would, no doubt, prove interesting and instructive. 



