1899-1900.] Dr E. Stewart MacDougall on Genus Pissodes. 329 
be laid near one another, owing to the sufficiency of room at the 
disposal of the larvae, the resulting tunnels show a star-like pattern. 
In young plants, however, the larvae on hatching tunnel upwards 
and downwards. A trail of brown bore-dust remains behind to 
map out the path of the larva. Arrived at the end of its gallery, 
the larva gnaws out a hole in the outer layers of the wood, and in 
this hollowed-out bed, protected by a cover of sawdust and wood- 
chips, the pupation stage is passed. These beds may be made from 
the upper part of the stem all down to the ground, and also an 
inch or two below ground. A very favourite place is immediately 
below the whorl of branches, where, in an infested plant, one is 
always sure to find several beds clustered together. 
How plentiful these beds may be may be gathered from this, 
that in a piece of Austrian pine taken in October 1897, measuring 
6 inches long and 1 inch in diameter, I counted no fewer than, 
fifty-seven beds ; another piece of a three-year-old pine held eight 
beds within a space 1J- inches long and J inch in diameter. 
Very often during the experiments I found that eggs had been 
laid and larvse developed on the thinner branches, sometimes on 
very thin twigs as well as on the main stem and thicker parts of 
the branches. The result was that when the larva came to gnaw 
out its bed in the wood the whole of the tissue in these thin 
twigs from centre to outside (pith and wood alike) was eaten away, 
and in its bed in the hollow, bounded all round only by a thin 
rind, the larva pupated. In such cases the merest pressure on the 
branch bent it at these hollowed-out places. More than once when 
examining my pines I bent the twigs by accident, squashing the 
enclosed larva or pupa. In nature the wind must, I think, not 
rarely break off the twigs at such places, when the recognition of 
the broken or blown-down twigs might prove helpful in calling 
attention to the pests. This use of the thinnest twigs for egg- 
laying in my experiment would be partly due to the beetles not 
having enough of egg-laying room in thicker parts. 
If one remove the chip-cover from the bed before beetle escape, 
the white pupa may be seen lying on its dorsal surface with the 
rostrum arranged along the under surface of the thorax. When 
the beetles are ready to escape, they bore a circular hole through 
bed-cover and bark. Just before and after emergence they are 
