li 
or cold would not be so likely to affect them, as would be the case with 
pupaa lying nearer the surface. Many, however, do not inter themselves 
so deeply, as we have found pupae just under the roots of the grass. 
Any advantage, too, gained by a very wet and mild season, would 
probably be more than counterbalanced by the extra activity of the mole, 
and other lovers of fat pupae. 
Some other ideas suggest themselves. Immigration can scarcely be 
an important factor in a species with a wingless $ . It has, indeed, 
been supposed, that a reinforcement of $ s might increase the fertility 
of a species, but it seems unlikely that hispidaria should have benefitted 
in this way, although, from its robust appearance, a long flight would 
appear quite possible. The sudden augmentation of numbers, it will be 
noticed, took place in a well-known locality, where the insect is found 
in greater or less numbers, (generally the latter) every year. An 
alteration in the fertility or irregular fertility of a species in different 
seasons, has been suggested, but I do not know whether there are any 
facts in support of this theory recorded in relation to the macro-lepi- 
doptera. It might be that an unfavourable change in the weather 
might retard oviposition by the ? , or even destroy her, and this may 
possibly exert a certain influence in some seasons. The day on which 
we found the single $ in 1890, was an example of such a change, the 
afternoon turning very cold, snow and hail falling fast, and being driven 
by a strong N.W. wind into the crevices of the bark. I have been told 
by friends who have reared the species, that the larva is very subject to 
the attacks of Ichneumonidae, Tachinidae, etc., but we know so little as to 
the relative abundance or scarcity of these parasites, that their influence 
must, I am afraid, remain an undetermined factor. 
Hispidaria is, I am given to understand, a very prolific insect, but 
it seems no marvel, when we consider the perils through which it has 
to pass, that so few reach maturity. The ova have to withstand the 
attacks of tits, creepers, spiders, &c.—By the way, the Paridae seem to 
find the forest tree-trunks a prime feeding ground in the winter months ; 
they rove through the woods in large flocks.—The larva? have to run the 
gauntlet of the inclemency of our springs, of Ichneumonidae, Tachinidae, 
birds, and other enemies; the pupae are beloved by the mole ; the imago 
emerges in a month so cheerless as is our customary February, and in a 
very dry or frosty season might even be unable to reach the surface. 
Our friends (or enemies) the tits may often be observed during the 
winter months searching on the ground and about the roots of the 
trees, and no doubt many a ? falls to their lot. But the prolificness of 
the species would render probable its appearance in unusual numbers, 
whenever the attentions of its numerous enemies was in any degree 
relaxed, or meteorological conditions were unusually favourable. It 
may be interesting to note in passing that another moth, Taeniocampa 
munda, was much more abundant than usual in the early part of 1893. 
Since 1890, this moth has been far from common, but last spring it 
might have been captured by hundreds at the sallows. Its larva feeds 
on oak, and undergoes pupation at the base of the tree, favouring 
similar situations to N. hispidaria. I fear, however, that we cannot 
arrive at any very definite conclusions as to the causes of the pheno¬ 
menal abundance of the last-named species last year. The only really 
determinable among the, perhaps, many determining causes, appears to 
be the favourable spring of 1892 for the development of the larva?, and 
