374 ROCKY MOUNTAIN LOCUST ROCKY MOUNTAINS Some curious changes often follow the -wake of these locusts, where they denude a country of its vegetation. Thus, the common purslane gets a start over other weeds, and the large green and black larvae of a common and pretty hawk moth (deilephila lineata), which feed upon it, abound to such an extent as to fre- quently cause unnecessary alarm. But the most striking change is the appearance of a fine grass unnoticed during ordinary seasons, which furnishes abundant and nutritious food for stock. This grass ia the vilfa vaginceflora, an annual which is common from the Atlan- tic to the Rocky mountains. The locusts kill out the blue grass by gnawing it down too closely, and the changed conditions give the vilfa temporarily the advantage in the strug- gle for existence ; but in a year or two the normal relations between species are restored. The parasites which aid man in subjugating Fio. 8. Locust Mite, greatly enlarged. Fto. . SUky Mtte. Natural size at Bide. this locust consist mainly of four species, two mites and two flies. The silky mite (tronibi- dium sericc.um), a small scarlet animal about two lines long, attacks the egg underground ; while the locust mite (astoma gryllaria), a still smaller species, of similar color, fastens in numbers on the body at the base of the wings of the mature insect. The anonymous tachina fly (tachina anonyma), an insect twice Fio. 10. Sarcophaga carnaria : a. Larva. 6. Pnpa. c. Fly. (The hair lines show average natural lensrth*.) d. En- larged head and flrst joint of larva, showing curved hooks, lower lip (o), arid prothoractc spiracles. . End of body of same, showing stigmata (f) and prolegs and vent. h. Tarsal claws of fly, with protecting pads. i. Antenna of same, enlarged. as large as a house fly but somewhat resem- bling it, fastens its eggs to both the young and the mature locusts ; the maggots hatched from these penetrate the body and devour the vitals of their victim, soon causing its death. Finally the common flesh fly (sarcophaga car- naria) deposits living maggots under the wings of the locust, which also in time succumbs to them. A partial remedy against the locust, in regions where it is not indigenous, is found in natural agencies. Climatic conditions are often unfavorable, and many animals and in- sects prey upon it. Almost all the birds of the western plains feed upon the locust and its eggs. The protection of the prairie chick- en and quail would be an excellent measure. A better means of preventing its ravages is the destruction either of the eggs or of the un- fledged young. The eggs being laid in mass- es just beneath the surface of the soil, usu- ally on high, dry ground, simple harrowing or shallow ploughing will break up the mass- es and expose the eggs to the desiccating and bleaching effects of the atmosphere, which are fatal to them. If deeply turned under by the plough, many of the eggs will rot, and the rest will hatch too late for the young to do serious damage. Ground thus treated should not be turned again in the spring. A few days' excessive moisture is also fatal to the eggs, and where irrigation is practised they may be very easily destroyed. The eggs, how- ever, are often placed where none of these means can be employed. After hatching, the young hoppers may be destroyed by heavy rolling, by collecting them into heaps and burn- ing them with coal oil, or into windrows of straw, which is then set on fire. The most ef- fectual way of destroying them is by ditching, especially where there is no hay or straw in which to burn them, as in western Missouri in 1875. A ditch 2 ft. wide and 2 ft. deep, with perpendicular sides, is an impassable barrier to the young insects. They tumble in, and as they accumulate die at the bottom. To pre- vent the intolerable stench, pits or side ditches should be dug into which they may be swept and buried. Hogs and poultry may also be turned out to feed upon them. Prof. Riley urges as a possible means of preventing locust incursions, that a thorough study of the insect in its Rocky mountain breeding places be made by the national government ; for " by learning just when and how to strike the insect so as to prevent its undue multiplication there, . . . we may hope to protect the fertile states to the east from future calamity." From time imme- morial locusts have been used as food in ori- ental countries, and it has been found that the Rocky mountain species makes a very good soup or bisque. ROCKY MOUNTAINS, a name applied indefi- nitely to a long series of mountain ranges west of the Mississippi, of a great variety of form and structure. The term Stony mountains was ori- ginally used without the intention of applying it to any one range or group of ranges. From the eastern slope, westward, we pass over range after range for 1,000 m. or more, until we descend the western slope of the Coast range to the Pacific. At least two thirds of the United States, an area of over 2,000,000
