Page:Popular Science Monthly Volume 86.djvu/269

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HEN one speaks of the insects of the Pacific, they are the insects of the Pacific shores and Pacific islands that one refers to. For with all the amazing adaptiveness of insects to variety of habitat and habit, and with all the pressure of enormous numbers of species and individuals to drive them far and farther and into all the available places of earth, the insects have, curiously, so far not invaded the oceans. Although they constitute of known living animal kinds a full two thirds, perhaps three fourths, they are restricted in habit to but one third part of the earth's surface, to wit, its dry land and fresh and brackish waters. The real salt sea is tenantless of insects. A few long-legged surface treading kinds are found on ocean waters far from land, but these are really inhabitants of surface sea-weed patches, which, like their freshwater cousins, the familiar water-striders or skaters of ponds and quiet stream-pools, can run or glide quickly over the water's surface, denting but not breaking the supporting surface film.

There are also a few small kinds which haunt the beaches and rocks between tide lines for sake of the rich harvest of food thrown up by the waves. Such a kind is a little long-legged fly with atrophied wings, which lives on the headlands of the California shore in the Monterey Bay region. When the tide is out it runs actively about, looking like a small slender-bodied spider, over the rough, damp rocks between tide times, seeking bits of organic matter thrown up by the waves that dash over the rocks at high tide. When the waters come back these odd little flies seek refuge under small silken nets they have spun across shallow depressions in the rocks. They cling desperately to the under side of the protecting silken mesh, while the great waves dash and break over them. Of course they are much of the time actually submerged in salt water. But they stand it.

Recently a similar and closely allied fly has been found on the shores of bleak South Georgia Island in the South Atlantic about 500 miles east of Patagonia. And another tide-rock fly of like habits is known from the cold and tempestuous Kerguelen Island of the South Indian Ocean.

The insects of the Pacific Islands are, however, more conspicuous by the kinds familiarly known all over our continent than by the sorts peculiar to the islands. In fact, what with the same old house-flies and blue-bottles, mosquitoes and fleas, cockroaches and bedbugs, and other familiar close companions of man, the insect fauna of a Pacific island or of the Pacific coast of America is likely to be disappointingly familiar and familiarly troublesome.