/4 A. E. GIBBS —SI REX NOGTILIO AND S. GIGAS 
and practically without legs. As it continues its excavation the 
maggot fills up the gallery through which it has passed with 
the rejected particles of wood, which are so tightly squeezed 
together as to necessitate the use of a bradawl or some similar 
instrument to clear it of the refuse. This can he well seen in the 
specimens of bored wood which I have brought for exhibition. 
When fully fed the larva pupates in a cell in the wood, from which 
the perfect insect, when it emerges, escapes by boring a clean-cut 
tunnel direct to the open air. Some of the wood at our Technical 
School had been sawn into planks, and these had been placed one 
above another against an inner wall of the building, so that after 
leaving their pupa-cases the imagines had in several instances to 
bore through a succession of planks to obtain their liberty. The 
tunnels made by the escaping flies are clearly shown in some of the 
pieces of wood now exhibited. It is a doubtful point whether 
the female ever deposits her eggs in a healthy tree. Some 
authorities tell us that she either selects one which is showing 
a ’ b 
Fig. 21 .—Sirex noctilio. a, male ; b, female. Three-fourths natural size. 
signs of decay, or places her eggs in a fallen tree. The silver-fir 
seems to be a special favourite with this species, but several other 
conifers are liable to attack. In England, although considerable 
damage is sometimes done to fir plantations, the injury caused is 
not so serious as is often the case in Continental pine forests. 
It will be noticed that I have been calling this insect Sirex 
noctilio and not Sirex juvencus, the name by which it is generally 
known. The Rev. E. D. Moriee, writing to the ‘Entomologist’s 
Monthly Magazine’ for February,* shows that the* latter appel¬ 
lation pertains to another species, and that the insects constantly 
recorded in this country as S. juvencus are the S. noctilio of 
Fabricius. The true S. juvencus is very rarely found in the 
Rritish Isles. 
During the time that I had Sirex noctilio under observation, my 
co-secretary at the County Museum, Mr. F. G. Kitton, brought to 
me a female specimen of an allied species, S. gigas, which had 
been killed in his wood-cellar, and a few days afterwards he 
* ‘Entomologist’s Monthly Magazine,’ 2nd ser., vol. xv, p. 34. 
