Читать книгу Intelligence in Plants and Animals - Thomas G. Gentry - Страница 19

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No more remarkable creature exists, perhaps, than the little Brachinus fumans, which is so very common in the early spring. Damp situations are affected by it, but it is seldom met with except by insect-hunters, for it conceals itself generally under stones, as many as a half-dozen individuals often being found in company in a single locality. Banks of tidal rivers afford excellent hunting-grounds in England for Brachinus, but in America low, dank woods and borders of streams are the places where one must look to discover its presence.

When once you have made the acquaintance of so remarkable a stranger you can never afterwards fail to recognize him in your travels. He is peculiar, but not at all distinguished in looks, as some of his brethren. Picture a yellowish-red beetle, with a bluish frock-coat, which his wing-covers resemble, and possessed of a short, narrow head, a heart-shaped prothorax, as the front of the chest-segments is called, and a long, broad abdomen, three times the size of the rest of his body, and you have a tolerably fair idea of Brachinus.

But it is not so much his odd shape as a most extraordinary property he possesses, which is singularly unique in the animal kingdom, that makes him an object of interest and curiosity. Deep down in his most marvellous body a fluid, highly volatile in its nature, is elaborated, which the little creature can retain or expel at his pleasure. It is only, however, when alarmed that he utilizes this fluid in small quantities in defense, but its effect is wonderful, for in coming into contact with the atmosphere it immediately volatilizes and explodes, looking very much like a discharge of powder from a miniature artillery. In consequence of this phenomenon the insect which produces it is popularly called the Bombardier Beetle.

BRACHINUS PURSUED BY AN ENEMY.

His Curious and Unique Method of Defence.

So small a coleopter, being scarcely one-fourth of an inch in length, and so comparatively weak, is likely to be attacked by the larger Geodephaga, or Earth Devourers, and especially by the Carabi, which inhabit similar retreats. But for this curious defence the smaller insect could have but the barest chance of living in the struggle for existence. Often have I seen a Carabus in hot pursuit of Brachinus. The chase is always an interesting one, and never fails, however frequently it has been observed, of attracting attention and exciting admiration. But the wide-awake, ever watchful Brachinus never loses his head for a second when thus pursued, but like the clever artilleryman that he is, awaits the opportune moment, and then pours a heavy discharge of his fulminating fluid into the very face of the enemy. Baffled, alarmed, Carabus desists from the attack, and backs slowly away from the tiny blue smoke, while Brachinus, in the confusion that ensues, escapes to some place of security for rest and protection.

Most skilfully has the artist delineated the scene. Carabus serratus, the pursuing beetle, is chasing the Bombardier, and has nearly effected his capture, when, all of a sudden, a discharge of artillery has stopped the pursuit, under cover of which the Bombardier will make off. Meanwhile the Carabus, exchanging his rapid advance for a retreat quite as rapid, throws back his antennæ, a sign of his defeat, and skulks away to recover his wonted self-possession.

The volatile fluid, which produces such curious effects, is secreted in a small sac just within the end of the abdomen. Not only is it capable of repelling the larger beetles by its explosion and cloud of blue vapor, but it is also powerful enough to discolor the human skin, as many who have captured Bombardier Beetles by the hand know only too well. Should the fluid get within the eyelids, the pain and irritation produced are very distressing. Some years ago the writer, while searching for carabi underneath stones and in creviced rocks, met for the first time with Brachinus, but was ignorant as a child of his obnoxious property. Placing a little fellow upon his hand for close examination, he soon experienced a burning and painful sensation of the ball of the eye, but did not for a long while attribute the cause to a discharge from the Beetle. Repeated investigations at very short ranges by means of a microscope were attended with similar results, till eventually an inflammation of the visual organs set in, accompanied by a blurring of the sight, which debarred him from reading and study for nearly a fortnight. One learns wisdom by experience, and the wisdom thus acquired serves for a lifetime.

Even Brachinus has learned by experience, doubtless, to be economical in the use of his resources. The whole of the contents of his tiny magazine are not ejected at one discharge, but there is sufficient to produce a series of explosions, each explosion being perceptibly fainter than its predecessor. By pressing the abdomen of the dead Beetle between finger and thumb these explosions may even be produced. In hot countries, where exceedingly large species abound, the explosions are said to be very loud, and accompanied with quite a cloud of blue vapor.