Homes Without Hands: Being a Description of the Habitations of Animals, Classed According to Their Principle of Construction
The leaves on the left hand were taken from the garden rose, and have been mined by the larva of another species of the same genus, Nepticula aurella.
This beautiful little moth derives its specific name from the peculiar coloring of the upper wings, which are bright chestnut, relieved by a broad band of gold across their centre. The tips of these wings are fringed, and the lower pair are nearly white, and edged with a fringe similar to that which has already been described.
As a general rule, the leaf-mining caterpillars are solitary, and if even two or three are found in the same leaf, each leads an isolated life, and does not inhabit the same burrow as its neighbor. There are, however, exceptions to this rule, as to most others, and certain species of leaf-miners inhabiting the henbane live harmoniously together between the membranes of the same leaf. They are larger than the ordinary species, and are remarkable for their power of burrowing into a fresh leaf when ejected from their former habitation, a power which does not seem to belong to the caterpillars of the Micro-lepidoptera.
As the meandering tracks of the Micro-lepidoptera upon the leaves of various plants are very similar in general aspect, I have caused figures of common leaf-rollers to be inserted in the illustration. If the reader will turn to pages 312–316, he will see an account of certain moths whose larvæ roll up the leaves in which they reside. The lilac leaf on the left hand of the illustration has been rolled up by the larva of a moth named Gracillaria syringella, the generic title being given to it on account of its graceful form, and the specific name because it is fond of frequenting the syringa shrub. The larva is shown just below, of its natural size, and the hole through which the perfect insect has escaped can be seen upon the rolled portion of the leaf.
On page 315 may be seen an account of the manner in which the larva performs a task so apparently impossible as rolling up a leaf of such great comparative size. When the little caterpillar is contrasted with the leaf on which it is at work, the contrast is almost ludicrous, for it seems nearly as impossible for so little a creature to roll up so large a leaf as for a man to roll up one of the armor-plates of an iron-clad ship. The manner by which this task is achieved is described on the above-mentioned page, and the reader will be the better able to understand the description if he compares it with the illustration.
The moth which has inhabited this leaf is called Gracillaria semifascia.
To return to our leaf-miners.
Although the greater number of these insects belong to the Lepidoptera, the rule is by no means a universal one. Many beetles are thus parasitic within the leaves of plants, and, as a general rule, they belong to the family of Curculionidæ, or weevils. There are also several species of dipterous insects which have this habit, among which may be named the CHRYSANTHEMUM FLY (Tephritis artemisiæ), which burrows into the leaves of the flower. There is also a genus of flies called Phytomyza, i. e., Plant-sucker, the different species of which select particular plants, and burrow between the membranes of their leaves. The holly, for example, is infested by one species, the honeysuckle by another, and the common hart’s tongue by a third.
WE must now glance at a few of the insects that are parasitic upon other animals. Their numbers are very great, but we must restrict ourselves to those which construct some sort of a habitation.
The only insect which can be said to be parasitic on man, and at the same time to form a habitation, is the celebrated CHIGOE (Pulex penetrans), otherwise called the JIGGER, or EARTH FLY. This terrible pest is a native of Southern America and the West Indian Islands, and is too well known, especially by the negroes and natives.
This insect, which is closely allied to the common flea, and much resembles it in general appearance, contrives to hide itself under the nails of the fingers or toes, usually the latter. Having gained this point of vantage, it proceeds very gradually to make its way under the skin, and, strange to say, does so without causing any pain. There is a slight irritation, rather pleasing than otherwise, to which a novice pays no attention, but which puts an experienced person on his guard at once.
The male Chigoe is innocent of causing any direct injury to man, the female being the cause of all the mischief. As soon as she is settled, her abdomen begins to swell until it becomes quite globular, and of great comparative size, and containing a vast quantity of tiny eggs. Pain is now felt by the victim, who generally has recourse to the skillful old dames, who have a kind of monopoly of extracting Chigoe “nests.” With a needle they carefully work round the globular body of the buried insect, taking great care not to break it, as, if a single egg remains in the wound, all the trouble is wasted. By degrees they gently eject the intruder, and exhibit the unbroken sac of eggs with great glee. To prevent accidents, however, the wound is filled with a little Scotch snuff, which certainly causes rather a sharp smarting sensation, but effectually destroys any egg or young insect that may perchance have escaped notice.
Europeans and natives of the better caste escape easily enough, because they always take warning by the first intimation of a Chigoe’s attack, and generally succeed in killing her before she has succeeded in burying herself. Moreover, the shoes and stockings of civilized man protect his feet, and the gloves guard his hands, so that the insect does not find many opportunities of attacking the white man.
But the negroes, and especially the children, suffer terribly from the Chigoe. Children never are very apt at sacrificing the present to the future, and the negro child is perhaps in this particular the least apt of all humanity. The Chigoe is in consequence seldom disturbed until it has made good its entrance, and even then would not be mentioned by the child on account of the pain which he knows is in store for him. But the experienced eyes of the matrons are constantly directed to the feet of their children, and if one of them is seen to hold his toes off the ground as he walks, he is immediately captured and carried off to the operator, uttering dismal yells of apprehension.
He certainly has good reason for his fears. The Chigoe nest is duly removed, and then, partly to prevent the hatching of any egg that may have escaped during the operation, and partly to punish the delinquent for his disobedience, the hollow is filled, not with snuff (which is too valuable a substance to be wasted), but with pounded capsicum. The discipline is certainly severe, but it is necessary. After a child has once paid the penalty of negligence, he seldom chooses to bring such a punishment on himself a second time, and as soon as he feels the first movements of a Chigoe, away he goes to have it removed before it can burrow under the skin.
If the Chigoe be allowed to remain, the results are disastrous. Swellings make their appearance among the limbs, the glands become affected, and if the cause is permitted to remain undisturbed, mortification takes place, and the sufferer dies. So the red-pepper discipline, severe as it may be, is an absolute necessity with those who are unable to reason rightly, or to exercise forethought for the future. Every evening the negro quarter of the villages is rendered inharmonious by the outcries of the children who have neglected to report themselves in proper time, and who, in consequence, are suffering the penalty of their negligence.
THERE are some insects which produce upon animals certain swellings which are analogous to the galls upon trees. Such, for example, is the well-known BREEZE FLY (Œstrus bovis), which is so troublesome to cattle. The larvæ of this insect live under the skin of the animal, and in some manner raise a large swelling, that is always filled with a secretion on which they live. In fact, the swelling is a gall produced on an animal instead of a plant, and the inclosed insect feeds in a similar manner upon the abnormal secretion which is induced by the irritation of its presence.
The larvæ are fat, soft, oval-bodied creatures, and are notable for the flattened end of the tail, on which are placed two large spiracles or breathing-holes.
Although the larva which inhabits the vegetable gall seems to have but small need of air, and to all appearance can exist without any apparent channel of communication with the external atmosphere, such is not the case with the inhabitant of the animal gall. An opening is always preserved in the upper part of the swelling, and the tail of the grub is tightly pressed against the aperture so as to insure a constant supply of air.
In the months of May and June these swellings may be found in great plenty. They are mostly seen upon young cattle, and, as a general rule, are situated close to the spine. So common indeed are they, that out of a whole farm-stock of cattle I have seen almost every cow under the age of four years attacked by the Breeze Fly, and counted from two or three to twelve or fourteen upon a single animal. It is said that as many as forty have been detected upon a single cow, but such an event has not come within my own observation.
The swellings caused by the Breeze Fly are called Wurbles, or Wornils, and can be easily detected by passing the hand along the back. Strangely enough, the cow does not appear to feel any pain from the presence of these large parasites, nor does she suffer in condition from them, although it would seem that they must keep up a continual drain upon the system. Indeed, some experienced persons have thought that, instead of being injurious, they are absolutely beneficial.
When the grub has reached its full development, it pushes itself backward out of the gall, and falls to the ground, into which it burrows. Presently the skin of the pupa becomes separated from that of the larva, and the latter dies, and becomes the habitation in which the pupa lives. The head portion of the skin is so formed that it flattens when dry, and can easily be pushed off, like the lid of a box, permitting the perfect fly to escape. Even when the insect is still in its pupal condition this lid can be removed, so that the pupa can be seen within its curious habitation. I may mention here that insects which are thus covered while in their pupal state, so as to show no traces of the creature within, are said to undergo a “coarctate” metamorphosis. Nearly all the diptera are examples of the coarctate insects.
BEFORE we close the subject of parasites, it will be needful to give a brief account of one or two parasitic insects which possess points of peculiar interest in the habitations which they make, or in the places wherein they find their abode.
One of these insects is a rather pretty beetle, termed Clerus alvearius. In its perfect state it is innocent enough, but in its larval state it is so destructive among the hives, that all bee-keepers will do well to destroy every Clerus that they can catch. It is generally to be found on flowers, licking up their sweet juices by means of a brush-like apparatus attached to the mouth. The wing-cases of most of the species are bright red, barred or spotted with purple.