| Fig. 494.—Gyrinus natator. | Fig. 495.—Larva of Gyrinus natator. |
The Gyrinidæ, which come very near to the Dytiscidæ, like water which is clear and a little agitated. They are small black insects, living in troops, and which swim with rapidity, describing incessantly capricious circles, which has gained for them the name of "Whirligigs." They are remarkable for the disposition of their eyes, which are double; so that the Gyrinidæ seem to have four eyes. The lower ones look into the water and watch for the prey or the fish that advances as an enemy; whilst the upper eyes look upwards towards the air, and warn the insect of the approach of enemies from above. To escape from fish, the Gyrinus jumps out of the water, and also makes use of its wings; to escape from birds it dives rapidly. This activity, and this double sight, make the capture of the Gyrini a task of great difficulty. They must be caught with a net. At the moment of being seized they emit a milky and fœtid liquid.
The females lay their eggs end to end, on the leaves of aquatic plants. The larvæ are long and narrow, and of a dirty white. They come out of the water at the end of the summer, and form for themselves a cocoon on the plants bordering the banks. After a month, the perfect insect is hatched, and plunges into the water. The Gyrinus striatus ([Fig. 496]) is found in the waters of southern Europe.
All these species are of small size, and do not exceed a fifth of an inch in length; but in the tropics we find Gyrini two-thirds of an inch long. One of these species, distinctus, exists in the little lake of Solazies, in Réunion Island, noted for its mineral waters. The visitors amuse themselves by fishing for this insect with a line baited with a bit of red cloth, which it attacks. It is found also in a mineral spring in Algeria. The Epinecti ([Fig. 498]) are large Gyrinidæ from Brazil, with very long front legs.
| Fig. 496.—Gyrinus striatus. | Fig. 497.—Gyrinus distinctus. | Fig. 498.—Epinectus sulcatus. |
The carnivorous land insects par excellence—those which are most formidable, on account of their ravages and voracity—are the Carabidæ. This family, one of the most numerous of the Order Coleoptera, consists of insects with long legs, and armed with powerful mandibles, suited for tearing their victims to pieces. They are the lions and the tigers of the Coleoptera, whilst the Necrophori and the Silphæ play the part of hyænas and jackals. The eyes of the Carabidæ are very prominent, which allows them to see their prey at a great distance. They take refuge under stones and under the bark of trees; but in fine weather they are also to be seen running along roads. Ardent and audacious, it is by no means rare to see them attacking species much bigger than themselves. The activity which distinguishes these insects is found also in their larvæ, which pursue living prey, instead of remaining shrouded in the midst of their food, like the larvæ of the Scarabæidæ.
These carnivorous insects are very numerous—a fortunate circumstance, considering the immense quantity of small noxious creatures, caterpillars, weevils, and an infinity of other parasites, the pests of agriculture, which they destroy. The popular prejudice, then, is to be regretted, which leads ignorant farmers to exterminate them. They ought, on the contrary, to be introduced into market gardens, as toads are, and as cats are into granaries. "The Carabidæ," says M. Michelet, "immense tribes of warriors, armed to the teeth, which, under their heavy cuirasses, have a wonderful activity, are perfect rural constabulary, day and night, without holidays or repose, protecting our fields. They never touch the smallest thing. They are occupied entirely in arresting thieves, and they desire no salary but the body of the thief himself." But ignorance destroys these useful hunters. Children, seduced by the richness of the elytra of the Carabi, amuse themselves in catching these vigilant protectors of our farms, without knowing the bad effect of what they are doing. Fortunately, education is spreading little by little in the country; the farmers begin to be awakened to their true interests, and to know how to distinguish the useful animals which it behoves them to preserve in their fields for the safeguard of their crops. In some places in France they have already made attempts to introduce the Carabidæ and the Cicindelidæ into gardens, and they have found them succeed very well.
The true Carabi are to be known by their oval convex body, their long antennæ, and elegantly-carved thorax. They are, in general, of more massive forms than the Cicindelidæ, which compose a kindred family. The latter form, in some sort, the vanguard and the light troops; the others, the heavy battalions. The Carabi coming out in general at night, or at least at twilight, and keeping themselves hidden under stones during the day, it is not easy to observe their manœuvres.
The Carabus auratus ([Fig. 499]), which abounds in fields and gardens on the Continent, may be considered as the type of this genus. It has elytra of a beautiful green, with three ribs, and the legs yellowish. When it is touched it disgorges a black and acrid saliva, and ejects from the abdomen a corrosive liquid of a disagreeable odour. It lives on the larvæ of other insects. It has been seen to attack even large insects, such as the cockchafer.
| Fig. 499.—Carabus auratus. | Fig. 500.—Carabus violaceus. |