worked chiefly in the laboratory, insist that it is the odor, not
the color of these insects, which is attractive, and some experiments
which have been made would seem to point in this direction. But the
creatures experimented upon most carefully were night-flying moths,
and it is quite possible that the sense of sight in the night-flying
moths has lost its vigor.

The great difficulty in understanding sexual attraction in insects, as
based upon beauty, lies in the undoubtedly lower development of their
nervous activity; in other words, in the apparent absence of anything
worth calling mind. I think no one imagines that a butterfly, looking
upon two other butterflies who are competing for her affections,
deliberates between them and determines to admit to the circle of her
friendship the more brilliantly colored male. Moths are so
irresistibly attracted to a light as to fly into it without apparent
power to withstand its influence. They repeat the flight again and
again until they are destroyed. If they react so vigorously to the
stimulus of the light, it seems not impossible that they may also act
vigorously to the stimulus of color pattern, and that the male most
beautifully colored, according to the nervous ideal of the female,
should win her unconscious regard. At least it is certain that, in
very many of the butterflies and moths, the attractive coloration is
chiefly displayed when they are moving actively about; and when they
alight and their enemies can the more easily capture them, they
conceal their brilliant colorings. Most butterflies are very brilliant
on the upper surface of the wings and very much duller on the under
surface. Hence in flight they show their colorings exquisitely, but
when they alight, and are thus more likely to be captured, they fold
the brilliant surfaces together in an upright position. In this way
not only is the dull side of the wings placed outward, but the wings
themselves are placed edgewise to the sky, and it is from this
direction that their enemies, the birds, are most likely to see them.
Once upon the wing these creatures display their beauty with much
greater safety because they can escape the birds very readily by use
of their exceedingly jerky flight. The butterfly's motion is as
irregular as any we have except the bat's. This eccentricity is one
great element in their safety, and makes it less dangerous for them to
display their attractive colorations.

One very large gr