BEETLES — GNATS 367 



On plants growing in stagnant or fresh water may be found the 

 hook -beetles, which when taken are quite dry to the touch, owing to 

 their being completely covered with air while in the water. Among these is the 

 horned beetle (Pamus prolifericornis), a species common in stagnant water, oval, 

 and almost cylindrical in shape, and of a greenish grey colour, covered with short 

 hairs, speckled on the elytra, slightly streaked, and a quarter of an inch long. The 

 bronze pond-beetle {Elmis ceneus) dwells on the rough stones in the bed of streams, 

 clinging to the bottom with its long legs or creeping slowly and clumsily under 

 water ; it is blackish, with more or less of a bronze-like glitter, and about an eighth 

 of an inch in length. Another river-beetle is Heterocerus marginatus, which is 

 nearly a quarter of an inch long, and digs itself holes in the mud, very often entirely 

 covering itself. It has a dense coating of short black hairs which stand erect, and 

 a few spots on the edges of the back, the corners of the thorax, the elytra, and legs 

 are pale yellowish red. 

 TMck-Legged Among beetles which live in water only as larvae, those known as 



Beetle. reed-beetles deserve particular notice. The pale coloured larvae, which 

 are half an inch long, live in the mud on the roots of white water-lilies, hog-weed, 

 and other aquatic plants. For the purpose of breathing, they use the air which is 

 always found in abundance in the air-canals of water-roots, obtaining this by 

 pressing into the plants two scythe-shaped, brown appendages, placed at the back 

 of the body. These are simply the edges of the orifice of the air-canals extended 

 along the body on one side ; by this pressure they open two longitudinal slits at the 

 back of these appendages, and draw in the air through these slits, while two small 

 orifices at the base of the appendages appear to serve for the purpose of exhalation. 

 The larva of the thick-legged beetle, which feeds on water-roots, constructs before 

 its metamorphosis a long, oval-shaped cell, which it fastens to the root so as to 

 enable it to bite into the latter, and thus let the air escape through the hole, ex- 

 pelling at the same time the water from the cell. When this is done, the larva 

 closes the cell, and thus surrounded by air begins its transformation into a pupa. 

 After the adult beetle has emerged, it eats its way out of the cell, and lifted by a 

 stratum of air, which clings to the short silky hairs on the lower part of the body, 

 rises to the surface of the water, where it may frequently be seen. Later on it 

 deposits its eggs near the leaves of certain plants, generally using for this purpose 

 the leaves of the white water-lily. These are bitten through in one place, in order 

 that the eggs may be glued on the lower side of the leaf in two curved rows close 

 to the hole. This beetle (Donacia crassipes), which is broad and flat, is metallic 

 green in colour with a violet reflection, and has silver hairs beneath, the legs and 

 antennas being reddish at their bases : the length is a little under half an inch. 



Of the numerous flies and gnats frequenting the neighbourhood 

 of water in central Europe, the common gnat (Culex pipiens) is one 

 of the best known and the most detested. Its larvae live in stagnant waters, 

 generally hanging on the surface by means of their breathing-tube, but diving at once 

 if the water be at all disturbed. This gnat, which is a quarter of an inch long, is 

 marked with two longitudinal stripes on the yellowish brown thorax, the back being 

 grey, the wings white, and the legs light grey. The female of this species lays 

 three hundred eggs, and the young are developed after the lapse of from four to 



