GIANT SIREX. 
86 
time to time sent me in the warm season of the year. In the last 
season, however, some more special observations were forwarded to me 
of their powers of destructiveness to Fir-timber, suggesting that it 
would be well for their attacks to be more attended to. 
The female of the Giant Sirex is from an inch and a third to over 
two inches in the spread of the wings; head black, with some yellow 
markings; and the body between the wings and the abdomen, excepting 
the first two and the last three rings (which are mostly yellow), black 
also. The abdomen (as figured above) ends in a long point, beneath 
which is, in its horny sheath, the strong ovipositor with which the 
insect bores through the fir-bark to deposit its eggs. The male is 
smaller, with the abdomen yellowish, excepting the first and last 
segments, which are black. 
Sirex juvencus. 
Common Steel-blue Sirex and maggot. 
The Sirex juvencus is a most variable insect, both in its size and 
colouring. The female is commonly blue-black, with brownish or 
rusty-colour in the legs ; the male blue-black, with the margin of the 
third and the whole of the four following segments red; the hinder 
shanks and feet dilated and compressed. 
The size varies from about half an 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 
