INTRODUCTORY CHAPTER.
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—
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 HummingBird 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 andmany 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 underthe 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 andmarkings 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 bodiesby 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, thepupa 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. Takingthe 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 themfrom 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.