. Un manuel pour l'étude des insectes. Les insectes. COLEOPTERA. Famille 523^ Dytiscidae (Dy-tis'ci-dae). Le Predaceoics sous-coléoptères si l'un va tranquillement une approche extérieure de l'eau debout, il peut être vu, les coléoptères ovale aplati de la tête en bas, suspendu à l'extrémité de l'abdomen à la surface de l'eau. Ces insectes appartiennent à cette famille. La plongée-prédateurs coléoptères sont habituellement brun noire et brillante, mais sont souvent marqués indéfiniment avec jaune terne. Ils peuvent être distingués de l'eau chasse-insectes, qu'ils ressemblent à s'affichent en général, par le thread-comme forme de l'un

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. A manual for the study of insects. Insects. COLEOPTERA. 523 Family Dytiscid^ (Dy-tis'ci-dae). The Predaceoics Diving-beetles If one will approach quietly a pool of standing water, there may be seen oval, flattened beetles hanging head downward, with the tip of the abdomen at the surface of the water. Such beetles belong to this family. The predaceous diving-beetles are usually brownish black and shining, but are often marked indefinitely with dull yellow. They can be distinguished from the water scavenger-beetles, which they resemble in general appear- ance, by the thread-like form of the antennae. The hind legs are the longest, and are fitted for swimming, being flat- tened, and fringed with hair. The middle and the hind pairs of legs are widely separated. This is due to the very large hind coxae which cover the greater part of the lower surface of the thorax. In the males of certain genera the first three segments of the fore tarsi are dilated and form a circular dislo upon the under side of which are little cup-like suckers (Fig. 630). In a few cases the middle tarsi are dilated also. The females of some species exhibit an ^^^' ^^°' interesting dimorphism in that some of the individuals have the elytra furnished with a number of deep furrows (Fig. 631), while others of the same species have them smooth. The diving-beetles abound in our streams and ponds, but they are more often found in standing water than in streams. When at rest they float in an inclined position, head down- FiG. 631. ward, with the tip of the hind end of the body projecting from the water. The spiracles open on the dorsal side of the abdomen beneath the elytra. By lifting the elytra slightly a reservoir is formed for air, which the beetle can breathe as it swims through the water. When. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the or

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• bookcentury1800
• bookdecade1890
• booksubjectinsects
• bookyear1895