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.