i6 
INSECTS. 
becoming pupae, and a little later in May emerging as full-grown saw-flies. The 
parasitic insect (Pachymerus calcitrator) figured in the illustration on p. 15 is one of 
the Petiolate Hymenoptera which seems to be exclusively parasitic on the present 
species. 
Tailed Wasps,—F amily Siricidie. 
In this family the female is furnished with a long, boring ovipositor for 
piercing the bark of trees; the eggs being laid in the orifice thus formed, and the 
larvae feeding on the wood. In the accompanying illustration of the boring 
apparatus of one species c, c, a, shows the whole of the muscular structure with 
which the boring is carried out. The perfect insects are 
usually of large size and conspicuously coloured. Among 
the typical forms the common tailed-wasp ( Sirex juvencus ) 
is a very rare species in England, although more plentiful 
on the Continent. The females, which are sometimes 
surprised in the act of depositing their eggs on pine-trees, 
may be easily caught, as the ovipositor can only be with¬ 
drawn with considerable difficulty. Indeed, the abdomen 
breaks in half, if the insect be roughly grasped. The much 
larger giant tailed-wasp ($. gigas) is far commoner among 
pine-trees, and is distinguished by its bands of black and 
yellow. Although it does considerable damage, it does not 
attack a perfectly healthy tree, unless recently felled. How 
long the larvae may live in the interior of the tree, and 
how long it is before the perfect insect appears, is not 
known, but cases are often quoted of this insect appearing 
in houses soon after their completion, having evidently 
emerged from the wood of the joists and beams. Another 
genus is well represented by the broad - bodied saw - fly 
(Lyda campestris). In this species the grubs feed on the 
young shoots of the Scotch fir, in which the eggs are laid. 
When hatched, the larvae spin a slight web in which they 
remain concealed, protruding the forepart of the body 
when feeding on the pine needles. When all the needles in the neighbourhood 
have been devoured, the web is extended, so that a great number of young shoots 
may be embraced and destroyed. The perfect insect is shining blue-black, with 
some of the abdominal segments reddish yellow. 
True Saw-Flies,—F amily TenthredinidjE. 
In this exceedingly numerous and widely distributed group, a well known 
example is the pine saw-fly ( Lophyrus pini), of which the larvae are sometimes 
found in such numbers in pine-woods, where they feed upon the needles, that the 
trunks are often coloured yellow and the branches weighed down. Towards 
the end of July, the perfect insect emerges by gnawing off the cap of the barrel¬ 
shaped pupa-case. The eggs are laid in incisions made in the needles, these 
BORING APPARATUS OF GIANT¬ 
TAILED wasp (much en¬ 
larged). 
