198 Rey. G. A. Crawshay on the 
wood, the second part of the burrow may run to the right 
or left (Plate XVI, a), or the entire burrow may run into 
the wood with a curve. 
The excavated wood-fibre the larva brings to the surface 
and with it fills in the remainder of the burrow in the bark, 
where it fed, up to the hole of entrance in the wood-cylinder. 
The work of excavation is carried on in the following 
way as I have observed under glass :— 
Biting away the wood-fibre before it, the larva sweeps it to one 
side with its mouth parts till a certain amount has accumulated, 
when, forming the first few segments into a curve J-shape, in which 
with the help of the side of the burrow it holds the wood-fibre 
(Plate XVIII, b—larva on extreme left), it backs along the burrow, 
drawing the wood-fibre with it. 
Having thus hooked the wood-refuse up the perpendicular and 
along the horizontal parts of the burrow, the larva backs out of the 
hole into the burrow in the sbark, still drawing the wood-fibre with 
it, and, by successive loads, fills up the burrow to the point of the 
hole of entrance in the wood, reversing its position and ramming the 
wood-refuse with its head. In other cases, when the larva has 
excavated a sufficient quantity to remove, it reverses its position in 
the bottom of the burrow at once and pushes all before it, advancing 
up the burrow head first. 
The burrow completed, the larva then excavates the bark opposite 
the hole in the wood-cylinder almost to the surface, leaving the 
imago very little to eat through to make its escape, and descends the 
burrow for the last time to pupate. 
While in process of excavating the wood, the larva 
swallows a certain portion of the wood-fibre, but it derives 
little if any nourishment from it, as is evidenced by the fact 
that if a larva which is not full fed be taken from its bark 
food and inserted in wood, it continues excavating rest- 
lessly and dissatisfied, till it wastes away and dies or 
makes a much-dwarfed imago. 
The burrow at this stage is clear from the entrance hole to the 
bottom. The larva then widens the bottom into a pupa-cavity about 
twice its own width and a little more than its length, using the 
excavated fibre to fill in the burrow behind with a good wad for 
about 3 in. Having bitten very smooth the walls of the cell it 
settles down, standing erect on the apex of the abdomen, and, with 
head pointing towards the future way of exit, now filled in, it awaits 
pupation (Plate XVI, b). 
