they would almost
certainly be killed. Some constant and easily perceived signal was
therefore necessary to serve as a warning to birds never to touch these
uneatable kinds, and a very gaudy and conspicuous colouring with the
habit of fully exposing themselves to view becomes such a signal, being
in strong contrast with the green or brown tints and retiring habits of
the eatable kinds. The subject was brought by me before the
Entomological Society (see Proceedings, March 4th, 1867), in order that
those members having opportunities for making observations might do so
in the following summer; and I also wrote a letter to the _Field_
newspaper, begging that some of its readers would co-operate in making
observations on what insects were rejected by birds, at the same time
fully explaining the great interest and scientific importance of the
problem. It is a curious example of how few of the country readers of
that paper are at all interested in questions of simple natural history,
that I only obtained one answer from a gentleman in Cumberland, who gave
me some interesting observations on the general dislike and abhorrence
of all birds to the "Gooseberry Caterpillar," probably that of the
Magpie-moth (Abraxas grossulariata). Neither young pheasants,
partridges, nor wild-ducks could be induced to eat it, sparrows and
finches never touched it, and all birds to whom he offered it rejected
it with evident dread and abhorrence. It will be seen that these
observations are confirmed by those of two members of the Entomological
Society to whom we are indebted for more detailed information.

In March, 1869, Mr. J. Jenner Weir communicated a valuable series of
observations made during many years, but more especially in the two
preceding summers, in his aviary, containing the following birds of more
or less insectivorous habits:--Robin, Yellow-Hammer, Reed-bunting,
Bullfinch, Chaffinch, Crossbill, Thrush, Tree-Pipit, Siskin, and
Redpoll. He found that hairy caterpillars were uniformly rejected; five
distinct species were quite unnoticed by all his birds, and were allowed
to crawl about the aviary for days with impunity. The spiny caterpillars
of the Tortoiseshell and Peacock butterflies were equally rejected; but
in both these cases Mr. Weir thinks it is the taste, not the hairs or
spines, that are disagreeable, because some very young caterpillars of a
hairy species were rejected although no hairs were developed, and the
smooth pupae