Page:Popular Science Monthly Volume 86.djvu/270

266 But this familiar character of the first seen and most often seen insects of the Pacific points an important moral to the student of insect distribution and of insect troubles. It is the moral of man's personal aid in the wide dissemination of insect pests. Wherever he goes, by wagon, train or ship, he carries the pests with him, colonizes them wherever he settles, and supports them in their new homes by his own presence and the presence of his domesticated animals, Ms quickly planted grains and vegetables, fruits and flowers.

So the casually inquisitive visitor to Pacific lands will find himself irritated by the same kind of fleas, mosquitoes, buzzing flies and biting flies, nocturnal bed-fellows, the same old croton bugs and black beetles and the rest that he knows in the east and middle west.

They have all come to California and Oregon and Washington, and gone on to the Hawaiian and Samoan and Philippine Islands, just as many of them came from Asia to Europe and Europe to the Atlantic and went on to the Mississippi Valley in earlier years. And this emigration and immigration by the side and with the aid of man accounts for a considerable and, from the economic point of view, a very important part of the Pacific insect fauna. For most of the worst insect pests of California and the rest of the Pacific coast are imported and comparatively recently imported species.

The most important single group of insects to the citrus and deciduous fruit growers of California are the scale insects (Coccidæ), small, degenerate, specialized, wax-covered and protected sap-sucking creatures, of hardly the seeming of an insect at all. The San José scale, the cottony-cushion scale, the black scale, the soft brown scale, the red orange scale, and all the rest of the scaly crew are ever threatening clouds on the fruit-grower's horizon. And he spends annually much time, energy and money in fighting back the swiftly multiplying hordes of these pests.

Now practically all of them are natives of other lands; they are man-aided immigrants into California. The San José scale, that once threatened the whole deciduous fruit interest of California, came from China about 1875. The cottony-cushion scale that similarly once threatened all the citrus orchards came from Australia about 1868. And the story of the coming, and settling, and finding the country good, of several of the other kinds is as well known.

But, fortunately, the economic entomologists have learned something to their advantage from this kind of insect immigration. They have learned deliberately to hunt for and import good bugs to fight the bad ones. For example, it was discovered that the Australian cottony-cushion scale, so dangerous a pest in this country, was not so dangerous in Australia, and this because of the active efforts made there by a certain kind of little black-and-red lady-bird beetle known as the vedalia. The