Insects : their life-histories and habits . Common May-fly [Ephemera vulgala) Larva of Water-beetle (Dytiscus marginalia. Nymphal skin of a Dragon-fly {JEschna I Water Boatman (Xoto- Water Scorpion (Nepa cinerea)necta r/lauca) INSECTS IN THE WATER 017 If we attempt a rough classification of water insects,we obtain the following table: Stages preceding the imago always aquatic;breathing dissolved air cutaneously or bymeans of skills. Plecoptera (Stone-flits) Ephemeroptera (May-flies) Odonala (Dragon-flies) Trickoptera (Caddis-flits) Neuroptera . , . Larva aquatic in one family—viz. the alder- f
Insects : their life-histories and habits . Common May-fly [Ephemera vulgala) Larva of Water-beetle (Dytiscus marginalia. Nymphal skin of a Dragon-fly {JEschna I Water Boatman (Xoto- Water Scorpion (Nepa cinerea)necta r/lauca) INSECTS IN THE WATER 017 If we attempt a rough classification of water insects,we obtain the following table: Stages preceding the imago always aquatic;breathing dissolved air cutaneously or bymeans of skills. Plecoptera (Stone-flits) Ephemeroptera (May-flies) Odonala (Dragon-flies) Trickoptera (Caddis-flits) Neuroptera . , . Larva aquatic in one family—viz. the alder- flies (Sialidie); breathing dissolved air bymeans of gills ; but pupa terrestrial. Hemiptera , , . About one-third of the bugs (sub-order Heteroptera) are more or less aquatic inall stages ; breathing atmospheric air. Colcoptera . , . About one-tenth of the beetles frequent water in one stage or another; someaquatic in all stages; breathing atmos-pheric air or (rarely) dissolved air bymeans of gills ( Gyrimis larva); pupausually terrestrial. Diplera ? ? • , Less than a quarter of the two-winged flies are
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectinsects, bookyear1913
