Many persons who know little or nothing about butterflies may be
tempted to make a collection of them when they find themselves in a
semi-tropical land, which yields in great profusion such beautiful
creatures, whose brilliant colouring when grouped together has so
pleasing an effect. To such, a slight sketch of the life of a butterfly
may not be unacceptable.
Butterflies and moths belong to the order Lepidoptera or Scale-winged
insects. The different stages of growth of these insects are called
the--
=_Ovum._= =_Larva._= =_Pupa._= =_Imago._=
Egg. Caterpillar. Chrysalis. Butterfly.
The body consists of three parts: the head, the thorax, and the
abdomen. There are two pairs of wings, the upper and the lower; or,
as they are generally called, the fore and the hind wings. These are
covered with a downy substance, like feathered scales, which are most
beautiful when seen under a microscope, and vary much in form. It is
in these that the colouring-matter resides, which gives the beautiful
colour to different species. Lepidoptera have six legs; in some,
however, the fore-legs are so short and inconspicuous that the insect
almost appears to have only four legs. The proboscis or trunk is a
long flexible double tube through which the animal sucks the juices
of the flowers; it is curled up under the thorax like a watch-spring,
and expands at will. It varies much in length both in moths and
butterflies. The antennæ are the horns or feelers of the insect, and
are believed to contain the organs of smell. They vary much in size and
thickness, and are most important as regards the classification of the
different species of Lepidoptera. They are generally of considerable
length in a butterfly, increasing in thickness at the end till a sort
of long knob is formed.
Moths are distinguished from butterflies by a few simple
characteristics, which can be seen at a glance.
First, with some few exceptions, of which the Humming Bird Hawk moth
is one, moths are always found on the wing at dusk, or at night,
whereas butterflies take their flight by day. Secondly, the moth either
folds its wings close to its side or else spreads them out flat. The
butterfly, when at rest, as a rule keeps its wings straight up, face
to face, or else keeps up a fluttering motion, continually putting
them in this position. Thirdly, the body of a butterfly is small at
the waist, while that of the moth is larger, and of a more uniform
size. The antennæ are the most distinctive feature, those of the moth
being fine and long, and having no knob at the end. In some species
they are short and finely feathered the whole length, terminating in a
sharp point; this feature is generally distinctive of the male sex; the
Rufescens moth being an example. The Skipper family have antennæ like
the butterfly, but the body of a moth.
The butterfly or moth lays its egg (not more than a pin’s head in size)
on that particular plant or tree on which the caterpillar, that it will
shortly become, feeds. These look of much the same form to the naked
eye, but when magnified they are seen to be of many different shapes,
some being conical, others round, angular and many sided, &c., &c.
The colours also of the eggs are various, but most frequently they are
yellow, green, or greenish white. A microscopic examination of these
will prove both interesting and instructive.
The caterpillars, as soon as they emerge from the eggs, the time of
which varies with different species, at once commence to eat, and
continue to do so voraciously till they turn to the pupa state. This
being the case, they must be constantly supplied with fresh food
when kept in captivity, once certainly, if not twice a day. There
are, however, one or two varieties which cease to eat, and lie in a
semi-dormant state for some time before taking the form of a chrysalis;
the caterpillar of the Exoleta moth is an example of this. The greatest
cleanliness, together with good ventilation, freshness of food, and
regularity in feeding, are essential to keep all caterpillars in health.
If we watch the creature feeding, we shall observe that it takes the
leaf edgeways between its two fore-feet, ceaselessly moving its head
up and down, and taking a large piece of leaf at each mouthful. Some
moth-caterpillars are night-feeders, and so hide themselves under the
thickest leaves on which they feed, or else bury themselves in the
earth till night comes again.
Cannibal caterpillars are to be found on the potato-plants; they are of
rather a reddish brown colour, from an inch and a half to two inches
in length. The author was not very fortunate in rearing them to the
moth-stage; it is said that they should be fed on the young larvæ, and
possibly the specimens had caterpillars to feed on that were too old.
There is room for interesting experiments in Teneriffe on one, if not
more, species.
Many of the caterpillars are most beautifully coloured and marked.
Those of the Hawk-moth are usually the most brilliant, but, at the same
time, they are most delicate, and require the greatest attention as
regards freshness of food, ventilation, and cleanliness.
Some larvæ shed their skins twice only, others moult seven times; but
the majority effect this change four or five times. This is rather a
laborious process for them, and sometimes proves fatal. During the
process they cease feeding, but commence again with renewed vigour
after the change has taken place. The colourings and markings of the
new coat often vary from those of the one cast off, and an experienced
entomologist can tell the age of the caterpillar by the colour and
texture of the skin in many varieties. When the creature has passed
through the larva and arrived at the pupa state, it has at first a soft
and tender skin, through which parts of the future butterfly can be
clearly seen; this soon hardens, however, and forms a case impervious
to rain or other atmospheric influences.
Before taking the pupa form some caterpillars creep into holes and
crevices of walls and old buildings, others bury themselves in the
earth; some envelop themselves in a tissue of silk which they spin as a
silkworm does, and this case is called a cocoon. Other species draw a
leaf round their bodies, fastening it together with silk-like threads,
and so making a complete shelter for itself. The Aurifera caterpillar
is an example of this type, being commonly found in Teneriffe on the
potato plant, from the leaf of which it constructs its house. Still
further varieties suspend themselves to a bough or leaf head downwards.
There are other varieties which suspend themselves from the centre of
their bodies by silk-like threads, and use much ingenuity in so doing.
Many caterpillars are smooth, others rough and hairy. The hairy
specimens vary much, the hair of some being soft, long, and silky,
others having short stubby spikes rather than hairs sparsely dispersed
over the body. The hairy species (the Rufescens moth caterpillar being
one) use their hairy coats as a slight cocoon, and the hairy coat also,
it is said, serves as a protection from birds; at the same time the
hairs cause great irritation to the human skin if the caterpillars are
handled too freely. The acrid taste of some also protects them from
feathered enemies. When the insect has remained in the pupa state for
a sufficient length of time, which varies according to species from
a couple of weeks to a few months, the process of throwing off its
skin is quickly performed. Weather has much influence on the period
during which the pupa lies dormant. The Teneriffe winter of 1892-93 was
particularly warm, and all specimens emerged to the butterfly stage
somewhat earlier than usual.
A few days before the butterfly or moth appears, the pupa becomes less
lively, and at last splits its skin down the middle of the back, and
the insect squeezes first its head and front legs through the aperture.
This aperture soon enlarges, the pupa skin being very dry and giving
little resistance, and the creature emerges, its legs clinging to some
substance so that the wings are in a suspended position. These are
quite small at first and wet, but they expand very quickly, acquire
their full size, and become firm and stiff as the animal flutters and
crawls about. The insect then emits a quantity of reddish fluid, and
in a short time it is able to fly away. The duration of the life of
Lepidoptera varies much, most species living a few days or a few weeks,
but some hibernate. The flight of Lepidoptera is a very distinctive
feature of the different species, the larger, such as the Plexippus,
Chrysippus and Pandora, seem to sail through the air, sometimes rising
to a great height. The Cardui and Huntera have a much quicker and more
jerky flight, and are troublesome to net. A great many of the large
moths may be said to rush along, the Convolvuli being a very difficult
one to capture, and often escaping when it seems quite within the net.
Taking the flight of the majority of moths and butterflies, they seem
to be more active and stronger on the wing in Teneriffe than those of
the same species in England.
The food of Lepidoptera consists of honey which they take from the
flowers, or else a moisture which exudes from trees or plants. Their
food is always of a liquid form, and is sucked up through the proboscis
or long tongue. The Convolvuli moth hovers at dusk over flowers,
inserting its very long tube into the extremity of trumpet-shaped
blossoms.
When forming a collection of the Lepidoptera of Teneriffe, it seems a
pity that so many insects should be unnecessarily caught and destroyed,
and the author would earnestly beg all lovers and collectors of
the beautiful creatures to bear this in mind, as some of the rarer
varieties may otherwise stand a good chance of being exterminated.
The “muchachos” (Spanish boys) are all too eager to supply any
collector with specimens for a few “quartos,” and bring many poor
mutilated insects in the hope of finding a purchaser. A refusal to buy
the much befingered and dilapidated creatures does not deter them from
further pursuit, as they only endeavour to catch a greater quantity in
the hope of at last getting a good specimen which will find a buyer.
If collectors would only net them themselves, and not encourage the
indiscriminate way in which the boys pursue them, it would greatly tend
to preserve the different species.