larger species of the group there is, in our islands, only one complete
life-cycle in the year, though the same insects in warmer countries may
be double-brooded. C.G. Barrett records (1893, vol. I. pp. 153-4) how in
the August of 1879 hundreds and thousands of 'Painted Ladies' (_Pyrameis
cardui_) migrated into the south of England from the European continent
where in many places great swarms had been observed early in the summer.
'These August butterflies, the progeny of the June swarms, coming from a
warmer climate, had no intention of hibernating, but paired and laid
eggs. Some of the larvae were collected and reared indoors [butterflies]
emerging in November and December, but out of doors all must have been
destroyed by damp or frost, in either the larva or pupa state, for no
freshly emerged specimens were noticed in the spring, and no trace of
the great migration remained.'

In September and October the pedestrian, even in a suburban square, may
see moths with pretty brown, white-spotted wings flying around trees.
These are males of the common 'Vapourer' (_Orgyia antiqua_), in search
of the females which, wingless and helpless, rest on the cocoons
surrounding the pupae whence they have just emerged, the cocoons being
attached to the branches of the trees where the caterpillars have fed.
After pairing, the female lays her eggs among the silk of the cocoon,
partly covering them with hairs shed from her body, and then dies. The
eggs thus protected remain through the winter, the larvae not being
hatched till springtide, when the young leaves begin to sprout forth.
The caterpillars, adorned and probably protected by their 'tussocks' of
black or coloured bristles, feed vigorously. Their activity and habit of
occasional migration from one tree to another, compensates, to some
extent, as Miall (1908) has pointed out, for the females' enforced
passivity; only in the larval state can moths with such wingless females
extend their range. The caterpillars spin their cocoons towards the end