LIBRARY

426
COLLEGE ENTOMOLOGY
sheathed with body and cemented down; rigid and immobile excepting the
apical abdominal segments; frequently attached by the cremaster, an anal
spine, hooks, or processes, or a pad, or by a pad and girdle.
The habits and life histories of butterflies and moths are so varied as to be
beyond the scope of this paper. Suffice it to say that only a relatively very few
complete life history studies have been made and there is yet much to be done
in this important field. Adult butterflies and moths are among the most delightful
and pleasing objects of nature and have long been of great interest and
concel11 to mankind. The caterpillars of many species are harmful in the sense
that they feed upon certain economic plants which through untold ages have
been theirs, plants which man has set apart for his own exclusive use during his
brief but dominant reign over nature. Only in unconquered tropical forests,
desert wastes, and useless swamps are these remarkable insects permitted to
perform their destinies without hindrance. But even here commercial hunters
are searching out beautiful iridescent species for the ephemeral uses of man to
such a degree that complete extermination awaits these beautiful creatures
which can never be replaced. To get some appreciation of butterflies and
moths, the student is requested to read The Life of the Butterfly by Friedrich
Schnack, translated by Winifred Katzin (Hought.on Mifflin, Boston, 1932),
which is written with a style and charm not excelled by any other writer.
While butterflies are largely diurnal and moths crepuscular and noct.urnal
in habits, these habits are by no means universal, especially in the moths
among which there are many day fliers. There is much variation in the range
of flight of different genera and families. Many moths are restricted to rather
circumscribed areas while butterflies often migrate hundreds and even thousands
of miles. The painted lady or thistle butterfly, Vanessa cardui (Linn.),
holds first place as a migratory species, but the cabbage butterfly, Pieris raplE
Linn., and many other species have extensive migratory habits. Among the
moths the silver "Y" moth, Plusia gamma (Linn.), migrates from the Mediterranean
region of northern Africa across Europe. In most continental areas
there are more or less distinct seasonal migrations which are marked in many
countries. Many such instances could be cited for both butterflies and moths.
Adults hibernate and restivate. Some of the most delicate species like the
common European brimstone butterfly or lemon bird, Gonepteryx rhamni
(Linn.), often lie frozen stiff under the snows of winter whereas the mourning
cloak, Nymphalis antiopa (Linn.), of Europe and North America seeks more congenial
weather in the southern limits of its range and is active most of the
winter. The monarch or milkweed butterfly, Danaus menippe (Hubner),
collects in great numbers on certain trees along the Pacific coast in California
during the winter months.
The eggs are laid at various seasons, spring, summer, and autumn. While
they are usually attached to the hosts, this is by no means always the case.
From a few to a thousand may be laid by a single female. Hatching does not
always correspond with emergence of the larvre, for in many cases the minute
fully formed first-instar larvre remain in the eggshells from midsummer or fall