Evening star., 1938-05-05

Butterflies and moths may be get
ting civilized.
Evidences that they are on the road
to an organized society comparable to
that of the ants and bees is adduced
by DR.. Frank Balfour- Browne, presi-
dent Of the Royal Microscopic Society,
and he believes that the steps they are
taking may be very close to the early
path of the more advanced insects in
a relatively recent geological period.
He defines as social organization
one in which individuals perform some
service for each other and for the group
as a whole. The criterion would not
be met by mere gregariousness
tudeS living in close proximity, but with
out any mutual service to each other.
Now it has long been assumed that
the development Of societies, either
among insects or vertebrates, depended
on the continued existence of the
mother after her eggs were Matched
and some attention, however crude on
her part, to the offspring. Thus COM
pact group of mutually related indi-
viduals could be built up and in the
course Of generations the relationships
could become closer and closer. But
among the moths and butterflies, the
English biologist finds, society is evolving
independently of the parent.
THE origin of social life among them,"
he says. lis to be seen in the larvae and
it is based upon the apparently ir-
relevant fact that many caterpillars Of
butterflies and moths produce silk. The
silk glands are often very extensive.
sometimes when Strengthened out being
two and half times the length of the
larva. They are salivary glands and
the saliva, leaving the tip Of the tongue
and coming into contact with the air,
sets as a thread, which the larva uses
in various ways.
Zone Is as a mat on the leaf surface
to give hold to the hooks on the feet.
Now as batch of eggs matches out
and the larvae remain together after
spinning such a mat, the mats overlap
and carpet of silk is formed. Then
the insects come within our definition
of q social insect, one in which the
members Of the family do something for
the common good. If it is objected
that this Is entirely unconscious aid
on the part of the larvae, my reply Is
that all the wonderful activities OF
termites, ants bees and wasps are In
stinctive, and therefore of exactly the
same order.
"The buff-tip moth lays its eggs in
patches and the larvae, on Matching,
appreciate one another'S company ana
spin common carpet web which they
eat up as they skeletonize the leaf. AS
they grow the carpet web is no longer
spun and the individuals tend to sepa-
rate, although there are still traces OF
the gregariouS habit and Weu-groWn
caterpillars meeting casually tend to
lie alongside while feeding or resting.
1.-THE cabbage butterfly also lays its
eggs in patches and the newly hatched
caterpillars, having eaten up their egg
shells, lay down a carpet web. But here
they remain together and continually
extend their carpet until they are al
most full grown. These two examples
seem to me to represent the earliest
stage of social life in larvae where the
connecting link, the silken thread, is
merely laid down upon the surface of
the food and eaten with it.
''The next stage is that in which
the larvae get underneath the carpet
and use it as shelter. They form it
around the food material, and, having
eaten out the food first covered, they
extend the web over more food. But
the half-grown caterpillars break up
into small parties and tend to become
solitary. Always. when full grown, they
are definitely solitary"
The next stage In this social evolution,