320 Proceedings of Roy cd Society of Edinburgh. [sess. 
to light, and its recognition suggested an excellent annihilative 
measure against the caterpillars. It was observed that the Nun 
caterpillars in the beginning of June, and for some weeks thereafter 
(in the hot weather), had the habit of leaving the trees in the day- 
time to hide in the moss below, perhaps to escape the heat of the 
sun, perhaps to avoid their enemies the parasitic Tachinidse flies. 
These caterpillars ascended the trees again at night to feed. This 
was one of the reasons which suggested the use of tar-rings here 
too. The descending larvae would not pass the ring, but collected 
over it, and thus thousands came into the power of those whose 
work it was to go round and destroy them, which otherwise, with- 
out the knowledge of this habit, would never have been reached. 
Now, although the Pissodes species have been long known as 
forest pests, the contradictory accounts given of their generation (and 
the flight times and length of time taken for development of such 
tree-infesting forms determine the time for trapping them by means 
of catch-trees), as well as my own observations of the species, satis- 
fied me that something was still to be discovered. The results of 
my experiments, especially as these prove a long-continued egg- 
laying on the part of the mother beetles, with a very long imago- 
life of both sexes, will, I hope, not only prove of interest on their 
scientific side, bub will place on a sure and logical foundation the 
defensive and offensive methods of procedure against these enemies- 
of our woods. 
As the best method of procedure against bark-boring beetles is- 
the employment of decoy stems or catch-trees or bark traps (the 
details varying with the species), a knowledge of the correct times 
when these should be prepared and revised and examined is the 
very kernel of the treatment. 
Some of the foremost economic zoologists on the Continent, in? 
their recommendations regarding tree-infesting Coleoptera, attach,, 
it seems to me, too great an importance to what they call 
the £ spring swarm ’ or the £ summer swarm 5 or the £ autumn 
swarm.’ The life-histories are written of as if the egg-laying of 
a species and resulting issue of the brood of beetles were confined 
to definite times, limited in extent. Those holding this opinion 
recommend the preparation of the decoy stems only against these 
swarm periods. It would be extremely agreeable if we could rely 
