The morning call., 1891-07-26
AERIAL SPIDERS.
Some Of Their Curious Ways and Remarkable
Productions.

Not content with living upon the earth, as
their structure especially fits them to do, the
family of spiders seeks also to conquer
both the air and the water. The peculiar
aquatic spiders which spin their webs at
the bottom of bodies of water have already
been described in previous issue. In
recent number of La Nature we find an in
teresting description from the pen Of DIR.
ii. de Varigny OF the aerial. or balloon, sDi-
ders, which, spinning their web in a tlssel.
or balloon of fibnrs, rise into the air. and are
sometimes waited immense distances by
the wind, much as the seeds of dandelions
or thistles are scattered over the land by the
feathery plumes with which they ara pro-
vided.
The studies of careful observers have
shown the way in which these little balloons
are made. The spider climbs to the top Of
shrub or some other elevated position, to
avoid collision with surrounding objects,
and spins thread which, as it is formed,
rises into the air, probably lifted up by the
current of heated air ascending from the
ground. After the first thread reaches the
length of foot or two the spider cuts 1t
off, and attaching 1t to some neighborlng
object, proceeds TO spin another. The
process is repeated until sufficient
number nave been formed to give SUI
ficient buoyancy to carry the spider on
them together, she lets them GO, and is
waited by the currents of air many miles.
These flying spiders have been observed AT
a height OF 1000 feet aud 1t is believed that
their Journeys often exceed 100 miles.
The cause of the buoyancy Of these little
spider-web balloons Is not thoroughly un-
derstood. Apparently the separate threads
sre charged with electricity as soon as
formed. and thus repel each other, to form
light, bulky plume, instead of adbering to-
thar in ma hnnVuneV IL
most probably due to the currents of heated
air which surrounds them, and in fact the
fibers themselves would become sufficiently
heated by the suns rays TO warm the
ing current. 1t has been noticed that
spiders only take their aerial journeys on
bright, sunny days, and that the shadow OF
a passing cloud, or the cutting off of the
suns rays by an artificial screen, causes the
threads to dIoop and collapse.
A remarkable observation upon these
spiders has been reported by NJ. Garry of
Valence, France, who states that he found
one of them spinning her web into the form
of twoFlittle hemispherical cups. or minia-
ture hot-air balloons. They were connected
together by separate threads, and the spider
could pass freely from one to the other
while en- voyage NJ. Garry believes that in
this way the spider was able, in small de-
gree, TO change the direction of her motion
through the air, the same as with the gas
balloons constructed by human beings,
which can sometimes be steered in course
slightly varying from that of the prevailing
wind.
This remarkable instinct of the spiders.
which causes them to make such extended
aerial journeys is undoubtedly of great adj
vantage to them in the struggle for exist
ence, and not only tends to spread the
species over wide areas of country, but fur
nishes quick and easy means of emigrat-
ing in times of scarcity of food to new
localities where food may be more plentiful
and spiders less abundant. How the in
stinct of aerial navigation was first devel-
oped, or under what circumstances the first
spider took her flight, is one Of those mys-
teries which are beyond our present knowl-
edge. The line dividing instinct from
reason is very indefinite one, and it is i'm
possible to say where one ends and the other
begins, Or in fact, to satisfactorily define at
all the difference between the two mani
festatiOns of the animal intellect. II is not
probable that the spider spins her threads
and constructs her balloon by the operation
of the same mental processes that a man
uses in constructing his larger and more
perfect aerial vehicles, but the exact way in
which they differ is something that is left
for future students of biology TO discover.
st. Paul Pioneer Press.