88 
PINE. 
“ In reply to your enquiries, I found the Sirex juvencus I sent you while 
I was staying with Mr. Nelson, of Friar’s Carse, about eight miles from 
Dumfries. We noticed that a Silver Fir of some eighty years’ growth 
was dying. Mr. Nelson had it cut down. All the upper part of the 
main trunk and all the branches were riddled with holes; in those 
cases the insect had escaped, but I cut several out, most of which 
would have got away in another day or two. Several trees of the same 
sort had failed, and been cut down in the last two or three years, but, 
as far as I could gather from the men employed, they were infested by 
an insect marked like a Wasp, probably the Sirex gigas, and they had 
not noticed this sort before. I think one or two Silver Firs only are 
left, and they look sickly.” 
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 effect 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 about in summer, and would gradually wash off without 
harming the surface to which it was applied. 
For general purposes, the only reasonably practical way of pre¬ 
venting spread of Sirex-infestation appears to be timely removal of 
infested timber, whether in the form of standing or felled trees, or 
fallen trees, or infested limbs. The wood need not be wasted ; what is 
of no use as timber should be split at once into small pieces for fire¬ 
wood (logs for burning), and, if found to be infested, it would be better 
to use this at once before the maggots have time to develop. Some 
could almost certainly be saved for service as timber, but the trees 
should not lie with the bark on, which attracts more attack. 
Felled trunks, and sickly or old trees in which the sap is not in 
vigorous flow, appear to be specially chosen for attack. I have myself 
known the Sirex gigas appear in such numbers from a Fir-stem lying in a 
timber-yard close to a Fir plantation that from twelve to twenty were 
caught in a few hours; but this is the only instance I have known of 
such great numbers developing at one time, that catching them as they 
appeared would be an easy remedy. 
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