. A manual for the study of insects. Insects. HEMIPTERA. 129 Family CORISID^ (Co-ris'i-dae). The Water-boatmen. These are oval, gray and black, mottled bugs, usually less than half an inch in length, which occur in the streams, ponds, and lakes of the whole United States. The characteristic form and markings of these insects are shown in Figure 148. These Water-boatmen have the body flattened above, and swim upon the ventral surface; in these respects they differ from the mem- bers of the next family. Fig. 148.—c^rzVa unduiata. The body of these insects, as they swim through the water, is almo
. A manual for the study of insects. Insects. HEMIPTERA. 129 Family CORISID^ (Co-ris'i-dae). The Water-boatmen. These are oval, gray and black, mottled bugs, usually less than half an inch in length, which occur in the streams, ponds, and lakes of the whole United States. The characteristic form and markings of these insects are shown in Figure 148. These Water-boatmen have the body flattened above, and swim upon the ventral surface; in these respects they differ from the mem- bers of the next family. Fig. 148.—c^rzVa unduiata. The body of these insects, as they swim through the water, is almost completely enveloped in air, which glitters like a silver armor. This air is breathed by the insects while they remain under water, and in good water it is purified by contact with the fine particles of air scattered through the water; so that the insects can breathe their coats of air again and again indefinitely. This is the case especially when they are in their favorite attitude, anchored near the bottom of a pond or aquarium. Here they will remain for a long time clinging to some object by their fore legs, and with their hind legs stretched out sidewise ; these they move frequently as when swimming. The result of this movement is to cause a current of water to pass over the coat of air, purifying it. The body of these insects with the air clinging to it is much lighter than water; consequently, w^henever they loose their hold upon the object to which they have been cHnging> they rise quickly to the surface, unless they prevent it by swimming. They occasionally float on the surface of the water, and can leap into the air from the water and take flight. They feed upon other insects and lay their eggs upon water-plants. All of the No'rth American species of this family belong to the genus Corisa (Cor'i-sa).. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these il
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectinsects, bookyear1895
