The Insect World. Figuier Louis

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СКАЧАТЬ only possess sufficient interest to claim our attention. From the Tanystomæ we select the families of the Asilidæ, Empidæ, and Bombylidæ. As types of the Brachystomæ we select the Leptidæ and Syrphidæ.

Fig. 33.—Tabanus autumnalis.		Fig. 34.—Chrysops cæcutiens.

      The chief characteristic of the Asilidæ is strength. All their organs combine to produce this quality, which they display only too much, being as formidable to cattle as the Tabani, but even surpassing those insects in natural cruelty.

      The Asilidæ unceasingly attack other insects, and even those of their own kind. Their trunk is strong; one of the fibres of the sucker is furnished with small points, turned back, which are intended to hold firmly to the body into which it has entered. They carry on their devastations in the glades of woods and on sunny roads.

      

      We will mention in this group Asilus crabroniformis (Fig. 35), an insect ten to twelve lines long, having a yellow head, black antennæ, and thorax of a brownish yellow. The three first segments of the abdomen are black, the second and third having a white spot on each side, the remaining segments are yellow. The wings are yellowish, spotted with black on the inner and hind margin. This species is common over the whole of Europe, and lives at the expense of caterpillars and other insects, of which it sucks the blood with the greatest voracity.

Fig. 35.—Asilus crabroniformis.		Fig. 36.—Bombylius major.

      The Empidæ live in the same way as the Asilidæ, but the males are chiefly nourished by the juices of flowers.

      

      "They wage war on other insects," says M. Macquart, in his "Histoire Naturelle des Diptères," "either when flying or running, and they seize their victims with their feet, which are formed in various ways, and well adapted for their purpose, but it is in the air that their hunting, as well as their amours, chiefly take place. They unite together in numerous companies, which during fine summer evenings whirl like gnats about the water's edge. A singular observation, however, that I have made on the Empis, is, that among the thousands of pairs that I have seen resting on hedges and bushes, nearly all the females were occupied in sucking an insect; some had hold of small Phryganeæ,[13] others of Ephemeræ, [14] and the greater part of Tipulæ."

      The Empidæ have the trunk bent down, and resembling the beak of a bird; but the Bombylidæ, on the contrary, have the trunk extended straight in front.

      The typical genus which has given its name to this latter group is easily to be recognised by the elegance of the fur which covers its body, the slenderness of its feet, and the length of its wings, which extend horizontally on each side of the body.

      Much more common in hot climates than in the North, these insects, the larvæ of which are not yet known, take flight in the middle of the day, when the sun's rays are hottest. They fly very fast, making a dull buzzing sound, and hover over flowers, from which they draw the juices without settling.

      Fig. 36 represents the Bombylius major, which is common enough throughout the whole of Europe. This insect is from four to six lines long, black, with yellow fur; the feet light yellow; and the wings have the edges bordered with a sinuous brown band.

      The genus Anthrax, belonging to this family, has a different form to Bombylius. The body is much less hairy; the trunk is short and concealed in the mouth; the wings, which are very large, are clothed, at least in the principal genus, in a garb of mourning, sufficiently remarkable, in which the combinations of black and white are admirably diversified.

      "Here," says M. Macquart, "the line which separates the two colours is straight; there it represents gradations, in other cases it is deeply sinuous. Sometimes the dark part shows transparent points, or the glassy part dark spots. This sombre garb, added to the velvet black of the body, gives the Anthrax a most elegant appearance; and while resting on the corolla of the honeysuckle and hawthorn to suck the juice, forms a most striking contrast, and sets forth its beauty no less than that of those lovely flowers."

      Anthrax sinuata is common in Europe.

      The family of the Syrphidæ includes three remarkable types, which we cannot pass over in silence. They are Vermileo, Volucella, and Helophilus.

      Vermileo de Geeri (Fig. 37), which inhabits the central and southern parts of France, is four or five lines in length. Its face is white; its forehead grey, bordered with black; the thorax of a yellowish grey, with four brown stripes in the male; the abdomen light yellow, spotted with black; and the wings glassy.

Fig. 37.—Vermileo de Geeri.		Fig. 38.—A species of Volucella.

      The larva of the Vermileo has a thin cylindrical body, capable of bending itself in every direction; a conical head, armed with two horny points; and the last segment elongated, flat, elevated, and terminated by four hairy tentacles; at the sides of the fifth segment may be observed a little angle, from which projects a horny retractile point.

      It is of very singular habits. It makes a small tunnel in the sand, having a conical mouth, where it waits, like the spider, immovable. As soon as an insect falls into the hole, it raises its head, and squeezing its prey in the folds of its body, devours it, and afterwards throws out the skin. It lives in this way for at least three years before attaining the perfect state.

      The Volucellæ (Fig. 38) have a strong resemblance to the humble-bee. Certain kinds make use and abuse of this resemblance to introduce themselves fraudulently into its nests, and to deposit their eggs therein. When these eggs have hatched, the larvæ, which have the mouth armed with two mandibles, devour the larvæ of their hosts, the bees. This is the return they make for the hospitality they have received!

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