. Entomology : with special reference to its biological and economic aspects. mphs (Fig. 170).The aquatic caterpillars of Paraponyx(Fig. 171) are unique among Lepidop-tera in having gills, which are filamentousin this instance. Caddis worms, enclosed in their cases,maintain a current of water by meansof undulatory movements of the body,and the larvse and pupae of most black flies(SimuliidcT, Fig. 230) secure a continuoussupply of fresh air simply by fasteningthemselves to rocks in swiftly flowing streams. Rectal respiration is highly developed in odonate and ephe-merid nvmphs. In these, the re
. Entomology : with special reference to its biological and economic aspects. mphs (Fig. 170).The aquatic caterpillars of Paraponyx(Fig. 171) are unique among Lepidop-tera in having gills, which are filamentousin this instance. Caddis worms, enclosed in their cases,maintain a current of water by meansof undulatory movements of the body,and the larvse and pupae of most black flies(SimuliidcT, Fig. 230) secure a continuoussupply of fresh air simply by fasteningthemselves to rocks in swiftly flowing streams. Rectal respiration is highly developed in odonate and ephe-merid nvmphs. In these, the rectum is lined with thousandsof tracheal branches, which arc bathed by water drawn in frombehind, and then expelled. All these kinds of respiration—cutaneous, branchial andrectal—occur in young ephemerid nymphs; while mosquitolarvre have in addition spiracular respiration. With the arrival of imaginal life, tracheal gills disappear,except in Perlida;, and even in these insects the gills are oflittle if any use. Marine Insects.—Except along the shore, the sea is almost. SimuUiim; A, larva; B,pupa, showing respira-tory filaments. ADAPTATIONS OF AQUATIC INSECTS I9I devoid of insect life, the exceptions being a few chironomidlarv;e which have ])een (hedged in deep water, and fifteenspecies of Halobafcs (belonging to the same family as ourfamiliar pond-skaters), which are found on warm smooth seas,where they subsist on floating animal remains. Between tide-marks may be found various beetles and col-lembolans, which feed upon organic debris; as the tide rises,the former retreat, but the latter commonly burrow in the sandor under stones and become submerged, for example the com-mon Anuyida iiiaritima. Insect Drift,—Seaweed or other refuse cast upon the shoreharbors a great variety of insects, especially dipterous larvae,staphylinid scavengers and predaceous Carabidse. On theshores of inland ponds and lakes a similar assemblage of in-sects may be found feeding for the most part
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Keywords: ., bookcentury1900, bookdecade1900, booksubjectentomology, bookyear1
