eggs in the roots, the larvae causing the presence there of globular
swellings or root-galls within which they live, pass through their
transformations and develop into wingless virgin females. These shelter
until February or March in their underground chambers, then climb up
the tree and lay on the shoots eggs, from which will be hatched the
grubs destined to grow within the oak-apples into the summer sexual
brood of flies.

The Lepidoptera afford examples of hibernation in all stages of the
life-history. In this order a few large moths with wood-boring
caterpillars, the 'Goat' (Cossus) for example, undergo a development
extending over several years, while at the other extreme a few small
species may have three or more complete cycles within the twelve months.
But in the vast majority of Lepidoptera we find either one or two
generations, definitely seasonal, within the year; the insect is either
'single-brooded' or 'double-brooded.'

Almost every winter one or more letters may be read in some newspaper
recording the writer's surprise at seeing on a sunny day during the cold
season, one of our common gaily-coloured butterflies of the Vanessa
group, a 'Tortoiseshell' or 'Red Admiral,' flitting about. Surprise
might be greater did the observers realise that the imaginal is the
normal hibernating stage for these species. Emerging from the pupa in
late summer or autumn, they shelter during winter in hollow trees, under
thatched eaves, in outbuildings or in similar situations, coming out in
spring to lay their eggs on the leaves of their caterpillars'
food-plants. The larvae feed and grow through the early summer months,
in the case of the Small Tortoiseshell (_Vanessa urticae_) pupating
before midsummer and developing into a July brood of butterflies whose
offspring after a late summer life-cycle, hibernate; while for the