THE FIREFLY
This insect is of little economic importance to us at present but its
peculiar habit of producing light makes it a very striking form and one
which deserves study. The firefly is a beetle, and begins to make its
appearance the latter part of June when the darkest nights may be one
solid glow of fire. They live largely in damp places and bottoms at
night are specked with their tiny flashes of light. The larval or grub
stage is passed on the ground beneath grass, weeds and rubbish where
they often prey upon other insects. In some cases the grubs may be able
to produce light though as a rule the luminous grub-like creature or
glow-worm is a wingless adult firefly.
OBSERVATIONS AND STUDIES
Watch for the first appearance of the fireflies in the evening and see
where they come from. Do they all appear at once or only a few at first?
Do they fly fast? How often is the light produced? Will they produce the
light while on the ground? When they fly do they stay near the ground or
high in the air? Do they light in trees?
[Illustration: Firefly beetles on sour-dock leaf.]
Catch one of the fireflies in your hat and examine it carefully. How
large is it? Describe briefly its size, shape and color. Are its wing
covers hard like other beetles? Where is the light produced? What color
is the light? Is it bright? Hold the firefly on the opposite side of a
sheet of paper and see if the light will show through. Try the same with
your hat, coat sleeve and other objects. This light is extremely
penetrating and unlike the light of a lamp is produced with the
generation of very little heat. Will it continue to flash while you hold
it? Are the segments from which the light comes the same color as the
other segments of the body? Crush the tip of the body between your
thumb and finger and see if the light continues to appear. How long does
it last? Collect a number of the fireflies and put them in a bottle and
see if the light is strong enough to enable you to read.
The firefly has proven to us that our methods of producing light are
extremely wasteful since much of the energy is lost in heat and it is
possible that through the lesson of the firefly we may some day be able
to produce better light at less expense.
[Illustration: Lower surface of firefly beetle enlarged to show the
light producing segments of the abdomen.]