312 TRANSACTIONS OF ROYAL SCOTTISH ARBORICULTURAL SOCIETY. 
enclosed in two horny side sheaths. The male is smaller, and 
has the rings of the abdomen reddish-yellow, except the first and 
the last, which are black. 
This year I have had S. gigas females sent to me from the follow- 
ing places:—Inchture, by Mr Gillespie, from a silver fir ; Yorkshire, 
in larch ; and two specimens from Edinburgh, one caught flying 
about in the street, and the other in a room which it had entered 
by an open window. These specimens were got in August and 
September. I also got specimens of attacked spruce from Perth- 
shire and Fife. 
Strea juvencus.—While in this insect, as in the last, there are 
variations in colour, the female is typically blue, with reddish 
legs, while the smaller male has rings, four to seven of the 
abdomen yellowish-red, The size varies from 4 inch to 14 inch, 
and the spread of wing from # to 2 inches. Specimens of jwvencus 
which I bred out from a pine log received this year from 
Mr Clark of Haddo gave the following measurements :—Males, 
}? inch, % inch, 1 inch, 1} inch; female, measured to tip of 
ovipositor, 13 inch, 
Now and again doubt is thrown on the fact of jwvencus being 
a British insect, but while it is certainly imported in timber, 
there is no doubt whatever that juvencus breeds in Britain. 
In last year’s Transactions it was reported from Dunraven 
(Glamorganshire) and Innerleithen. I have records in my notes 
of its capture from two localities in Midlothian, viz., Cramond 
and Roslin; while this year Mr Clark has taken many specimens 
at Haddo, Aberdeen, and Mr Leven has sent it to me from St 
Quinox, Ayr. Mr Philip notes a capture in County Galway. 
In her “Manual of Injurious Insects,” Miss Ormerod reports it 
from Gilgarron, near Whitehaven. 
An extremely interesting find is that of Mr Mitchell’s at 
Dunraven. Last year Mr Mitchell sent to me an Ichneumon 
Fly with the following note :—‘I found it apparently sending its 
ovipositor into the bark of a larch post which contained Sirea 
> This Ichneumon was Rhyssa perswasoria, a most hand- 
some insect, which is parasitic on Sirea juvencus larve. LRhyssa 
bores with its long ovipositor into a tree where the wood-wasp 
larvee are at work, and lays an egg in the tunnel of the wood- 
wasp. When the Rhyssa grub hatches, it proceeds to feed on 
the grub of the wood-wasp, which is thus destroyed. The 
ovipositor of /thyssa is very long, and sometimes this Ichneumon 
larvee.’ 
