A DESTRUCTIVE FAMILY
They went out to the garden and Uncle Paul hunted for some time in the
cabbage bed before he found what he wanted.
“Here is the caterpillar we were talking about,” he announced at last.
“It is of a delicate green color with three yellow stripes running
lengthwise. Now you must make the acquaintance of the butterfly. Jules,
go and bring me the net.”
Uncle Paul had a large gauze net, the mouth of which was attached to a
hoop of coarse iron wire fastened to the end of a long stick. That was
his butterfly-net, and in his leisure moments he used it for catching
butterflies, that he might destroy them before they laid their eggs on
the plants in the garden. The more butterflies destroyed, the fewer
hundreds of caterpillars a little later. Jules came back with the net,
but the chase did not accomplish the desired result, though another
butterfly was caught very much like the one they were after.
“We must be content with this,” said Uncle Paul. “My butterfly-hunting
of the last few days seems to have left us none of the sort I am
looking for; so we will not waste any more time.
“The insect I have just caught is known as the cabbage-butterfly. Its
wings are white, the forward ones having black tips and two or three
spots of the same color in the middle.”
“I see that butterfly everywhere,” declared Emile.
“It is in fact one of the most widely prevalent species. Its
caterpillar is greenish, marked with black dots and three longitudinal
yellow stripes. It does not spin a cocoon for its metamorphosis. The
chrysalis is spotted with yellow and black, and is found near where the
caterpillar lived, suspended from a wall or a tree in a very ingenious
manner. Before shedding its skin the caterpillar emits its small supply
of liquid silk, gluing the end of its tail to the spot it has selected
and then spinning a fine band which it passes across its body,
fastening the two ends at right and left on the stone or the bark to
which it is clinging. These preliminaries concluded, the chrysalis
stage is reached, the chrysalis being held firmly in place with its
lower end glued to the supporting object and its upper half kept from
falling by the silk band.”
“Without any cocoon to protect it?” asked Emile.
“Without any cocoon whatever; hence it is called a naked chrysalis.
Many other caterpillars adopt the same method: having only a scanty
little drop of liquid silk, much too small a quantity for spinning a
cocoon, they content themselves, when their metamorphosis approaches,
with gluing their tail to some object and supporting themselves further
with a narrow band. It is to be noted that butterflies from
caterpillars that do not spin cocoons all have very slender antennæ
ending abruptly in a rounded protuberance or swelling, and that they
fly by day in the brightest sunshine. They are butterflies proper, as
distinguished from moths. These latter have the chrysalis enclosed in a
cocoon, and their antennæ are sometimes of a feathery appearance,
sometimes spindle-shaped, or they may take the form of elongated clubs,
or, finally, they may be thread-like, tapering but little toward the
end. They fly mostly in the evening twilight, or even in the night.
Compare the antennæ of the cabbage-butterfly with those of the
silkworm-moth or the leopard-moth and you will see how easy it is to
distinguish a butterfly from a moth, a cocoonless from a
cocoon-spinning insect.”
“Then that’s all you have to do—just see whether the antennæ end in a
little round swelling,” said Jules.
“With something on the antennæ,” repeated Emile, “no cocoon; without
that, a cocoon. How easy it is!”
“As the youngest and giddiest of my hearers has understood my
explanation so well, I will pass on. Let us return to the butterfly
whose caterpillar is so interesting to Jules because it eats
indifferently cabbages, turnips, radishes, nasturtiums, and mignonette.
This butterfly is very much like the cabbage-butterfly. It too is
white, with black spots on the forward wings, but not of so deep a
shade. Furthermore it is about a third smaller. It is called the
radish-butterfly. To distinguish these two species, so much alike in
coloring and both feeding on the same plants, gardeners call the former
the big cabbage-butterfly, and the latter the little
cabbage-butterfly.”
“I know those butterflies,” Jules interposed. “Many a time I’ve seen
both kinds on the flowers in the garden, and I got them mixed because
there is hardly any difference in their color. Now I shall know how to
tell them apart. The larger one is the cabbage-butterfly, the smaller
the radish-butterfly.”
“You must bear in mind that the words cabbage and radish used to
designate the two butterflies do not mean that the caterpillar of the
one eats exclusively cabbages and that of the other only radishes. As a
matter of fact, the names could be reversed without any impropriety,
for both caterpillars, as occasion offers, feed on either the cabbage,
the radish, the turnip, or some other cruciferous plant. But let it be
noted also that these two terms have been chosen as substantially true
to the facts, though likely to mislead if taken in too literal a sense.
“The same remark applies to a third species, the turnip-butterfly,
whose caterpillar feeds not only on the leaves of turnip plants, but
also on those of the nasturtium, the mignonette, the radish, cabbage,
and many other crucifers. It is of about the size of the
radish-butterfly, and its wings are white with greenish veins
underneath. The forward wings have also black spots on their upper
surfaces. The caterpillar is slightly hairy and of a uniform green
color with no yellow stripes running lengthwise.”