Evening star. [volume] (Washington, D.C.) 1854-1972, 1906-06-09
THE MOTH AND THE FLAME.
Why Insects Hover About a Light
Until Burned.

From the Scientific American.
Why does a moth fly toward a flame?
Because 1t is inauisitive. was the rather
puerile answer given by the great Ro-
names. Because of some inexplicable In
herited instinct. was the reason advanced
by other naturalists. Because 1t Is the
nature of the insect, was third and
equally unsatisfactory reply. One reason
was as good as another. but that OF Ro-
names undoubtedly carried off the popular
palm. Perhaps we owe 1t to him that
moth and the flame have pointed many
moral and adorned many a sad tale of
curiosity tragically satisfied.
The investigations of Prof. Jacques Loeb
bid fair to relieve the moth of the moral
burden that has rested on Its wings. Prof.
Loeb has proved very conclusively that
moth in common with many Insects, mes
toward a flame for the same reason that
some plants turn their leaves toward the
light, "Heliotropism" Is the awesome
name in which this tendency OF plants ana
animals rejoices.
1t happens that there are TWO kinos OF
heltotropism If your moth or bug mes
toward the light it is positively heiiotropic'
If. like the earthworm. 1t shrinks from the
glare. 1t is negatively hehotropic- fiants'
too, may be classified into these divisions;
Just as some flowers open only by oay ana
others only by night so some moths ny
only by day and others only by night
The results of Prof. Loebs experiments
explain with astonishing simplicity the
causes of June bugs merry antics as
we'll as the apparently aimless movements
of squrmng, newborn vermln insects, II
seems move In the direction OF the hgnt
RAYS that fall upon them Change the posi-
ton of the light and the insect changes It's
course likewise. But the light must be OF
a certain Intensity to produce very
marked effect Suppose that In your ex-
periments you exposed your bug to dif-
fused light He would move toward the
light to be sure; but he would creep to"dfd
IL rather leisurely. Expose MIN 10
bright glare. however, and he VIII hasten
toward it with cheerful rapidity. That Is
WHY winged insects fiutter gayly about IN
direct sunlight Curiously enough, the IN
fiuence of light Is limited by atmospheric
temperature.
From the circumstances that insects tend
to arrange themselves and to move In the
direction of light it would almost follow
that their structure must have something
to do with their heliotropism. And such
Prof Loeb's experiments prove TO be the
case The head of insect Is much more
sensitive than the tall Here the omna-
present skeptic will probably remark That
an insect sees with his head and not with
him tall and that Romanes may be right
after all But such VIGOROUSLY blind ami
mails as the earthworm and other eyeless
creatures are far more responsive to light
at the head than at the tail. The mere
possession of sight cannot therefore. &C
count for the earthworms avoidance OF
light or for the moths apparent liking
for it.
Sometimes 1t happens that insect is
stimulated by light only at certain periods
of its existence. In winged ants, for ex-
ample the period comedies with the time
of the nuptial flight, in plant lice with the
appearance of wings and in some larvae
when full growth has been attained. Oc-