The genus to which the principal species of locusts of the United States belong is calopte nu.% and it comprises 29 species, as described by various authom, but it is thought that several of these upon further examination will he found mere varieties of closely allied species. Of these nearly all are local, and not greatly destructive; for instauce, C. floridans has been found only in Florida; C. griseus, only in Ohio; C. reptetus and C. scriptus only in the n.w. portion of Washington territory, aud others in other regions. Only three species are so nearly allied as to require careful examination for their dis tinction from one another; viz. the Rocky-mountain locust, ealoptenus spretus; the lesser locust, ealoptenus adanis, o'f the eastern states as well as western states and terri tories; and the red-legged locust, caloptenus femur rubrum. Some of the general charac teristics of the genus caloptenus are as follows: head subglobular, front vertical or nearly so; vertex narrow between the eyes, being a little less than the eye itself; sides parallel, flat or slightly concave, and nearly perpendicular; dorsal surface nearly flat; the elytra and wings extend to or beyond the tip of the abdomen, the elytra being nar row, with one exception (C. bivitatus), and the wings transparent in all the American species, with sometimes a bluish tinge. Abdomen usually subeylindrical, having no distinct keel above; that of the male enlarged at the tip and curved upwards, tlie last segment being sometimes truncated, sometimes notched. Posterior thighs stroll," and much enlarged near the base; the external surface more or less convex, and in the female generally lon,ger. Most of the _American species have the upper portion of the inner face of the posterior thighs marked with three oblique dark bands, the one at the base less distinct; antennm filiform and slender, much shorter than in the family locustidce or so called true grasshopper. The following are approximate measurements of the insect taken from an extensive table made by prof. Riley. Female: whole length to tip of elytra, to 14 in., the elytra projecting from 0.13 to 0.28 in. beyond the tip of the abdomen. Length of male to tip of elytra, 1/1,,- to 11 in.; projection of elytra beyond abdomen, 0.2 to 0.3 inch. The species most closely allied to C. spretus of Thomas is C. adanis of Riley, which is at once distinguished from C. femur rubrunz by the notched last joint of the abdomen of the male, and by greater relative length of wings, which extend nearly 'one-third their length beyond the tip of the abdomen in dried specimens, and also by the larger and more distinct spots on the wings. From both species it differs by its smaller size, and also by the more livid color of the dark, and paler yellow of the light, parts. Measurements of the male to tip of elytra, 0.84 to 0.93 to 0.95 to 0.98 to 1 inch. C. femur rubrum is larger than C. atlanis, but the elytra are shorter in proportion, some times in the female not reaching beyond the tip of the abdomen, the whole length to tip of elytra being from 1.04 to 1.22 inch. The C. femur rubruin is generally called the common rekl-legged locust, and C. spretus is known by tile several names hopper, army grasshopper, red-legged locust, Mormon locust, western locust, hateful grasshopper, and Rocky-mountain locust, which latter is the Inost appropriate name. The history of the Rocky-mountain locust, the specially destructive species, is much like that of the old-world locust. It breeds over vast areas and often migrates in immense swarms for hundreds of miles beyond its usual habitat, but the American locust prefers rather cooler latitudes than the old-world insect, a large portion, nearly one-third, of its permanent breeding grounds lying iu British America about the head-waters of the tributaries of lake Winnipeg. IN ot much can be said about the movements of the Rocky-mountain locust previous to 1864, and it is questionable by the commission whether it may not have increased in some regions since the settlement and improvement of the country, which has given them more subsistence. Neill's history of Minnesota mentions the invasion of that district of country by vast swarms of grasshoppers in 1818-19, which devastated the country and often covered the ground 3 or 4 in. deep, and in 1820 they ravaged the western counties of 3Iissouri. In 1842 locusts again appeared in Minnesota and Wyoming, and iu 1845 in Texas, and again in 1849. They have appeared in Utali from 1851 to 1877, except in 1873-74, and a portion of this territory forms one of the per manent breeding-grounds. From one year to another they have visited various portions of the territories and states. A notable locust year was 1866, when the insects swarmed over Kansas, Nebraska, the western counties of Missouri and n.e. Texas, and in Iowa, 31intiesota, Colorado, and Utah. They often delayed the railroad-trains in these parts by lubricating the rails when crushed. In 1870 locusts were not plentiful, but in 1870— 71 they began to increase, and in 1873 they again wrought serious ravages; but the most disastrous locust year which has been known in the country was 1874, vast destruc tiVe swarms invading settled portions of the Mississippi valley w. of the 94th meridian. Colorado, Nebraska, Kansas, Wyoming, Dakotan, _Minnesota, Iowa, Missouri, New _Mexico, Indian territory, and Texas were overrun by swarms from the n.w., from Mouthna and British America. The loss in this region was estimated at $50,000,000. In 1875 the young insects hatched in immense numbers over an area embraced by about 300 in. of latitude and 250 of longitude, embracing portions of Nebraska, Kansas, and
Missouri, the two western tiers of counties of 3Iissouri and the four tiers of counties in Kansas w. of Missouri suffered the most, about 750,000 people becoming destitute or suffering. In 3lissouri alone prof. Riley estimates the loss to have been $15,000,000. In Mar., 1877, prospects were bad, but there was an unusual rain-fall in April, May, and June, and much of the country along the Missouri river was flooded, and the weather -was cool over Colorado, northern Utah, Montana, and British America. The young insects died in vast numbers when they hatched, and few of them lived to acquire. -wings. South of 40° of latitude, late in May and early in June, they flew toward the n.w. to Dakotah and 3Iontana, whence their progenitors came.
The permanent breeding-grounds of the Rocky-mountain locust were not defined until the U. S. entoinological commission made their investigation. Vague ideas were entertained, and it was known that many of the swarms came from the n.w., but there was no definite information. It was ascertained that the area in which the locust breeds each year is about 300,000 miles. They do not cover this area in breeding, but may breed any year in any part of it. It is the permanent habitat, but the most favorite breeding-grounds within the area are the river-bottoms and sunny slopes of uplands, or the gra.ssy regions among the mountains, rather than over the more elevated, dry, and bleak plains. In central Montana the breeding-grounds are in the valleys of the Yellowstone, the upper _Missouri, Gallatin, 'Madison, and Jefferson rivers and the grassy plains along their tribu taries. These levels lie below 6,000 ft., mostly between 3,000 to 5,000 feet. The per manent area principally lies e. of the main Rocky-mountain range, between meridians 102 and 114 w. of Greenwich and between lat. 40° and 50° north. Farther w., between lat. 42' and 45° and long. 114° and 118°, there is a strip of 60 m. wide by 200 long at the head waters of the Snake river, a tributary of the Columbia, which is a permanent breeding ground. A subpermanent region, in which the insects breed more or less continuously, extends to the e. of the permanent region from 200 to 400 m., between parallels 39° and 53' of latitude. .A. temporary region extends to the le-alley of the n. Mississippi, passing through the states of Minnesota, Iowa, Missouri, and the north-western counties of Arkansas, and through Texas to the gulf of Mexico, thence n.w., passing through New 3Iexico, Arizona, Nevada, thence n. through Oregon and Washington territories to the main Rocky-mountain range in lat. 49°.
The locust is the only truly migratory insect, although swarms of butterflies have been known to fly short distances in the Mississippi valley. The locusts of the old world have been known to fly into central Europe from their permanent breeding-grounds in cen tral Asia. In North America they often extend their flights over a distance of 1000 to 2,000 m., or from Montana to Missouri, and even to Texas. The flight generally takes place during the day, commencing early in the forenoon and ending for that day at about five o'clock in the afternoon. The rate of travel varies from 3 to 20 m. an hour, depending on the wind. Sometimes those which cotnmence to fly in Montana the mid dle of July may not reach Missouri till Aug. or the fore-part of September. The svvarms are designated, according to their origin and direction, invading swarms, or those which come in vast numbers from their permanent breeding-grounds; returning swarms, or those which, having batched in an invaded district, return, as by instinct, to the per manent breeding-,grounds; and local flights, or those to-and-fro movements of insects hatched in an invaded district.
The height in which the migrating swarms move has been the subject of observation, and differs accordiuo. to locality, vastness of numbers, and direction and height of air currents. The signa°1-service officer at Bismarck observed a swarm moving above the cutnulus clouds. One observer states that in 1868, when upon the snowy raw-res e. of Middle park, and on Long's peak, there were daily flights of full-grown gras6shoppers as far as the eye could reach from the loftiest summits. Another, from Parry's peak, in 1872, speaks of them as filling the air like snow-flakes, far above the summit, 18,333 feet. It has been observed that a sudden change of wind generally brings a flying swarm to the ground. When the wind returns to the direction in which they were going they will again rise and pursue their flight. Repeated observations have con firmed this statement. A fall of temperature always bt•ings a swarm to the ground, and this is thought to be the chief reason of their alighting in the evening. Flights, how ever, have been known to take place at night, or to continue during the night when the -weather is warm. The opinion has been formed by some that the locust has but little power of flight except when aided by the wind, while others think it capable of sus tained flight even against a gentle wind. The truth lies between these extreme views. The migratory locust has considerable power df flight for so small an animal, but would make comparatively little progress, and not prove to be the devastator that lie is except for the wind. It has been observed that locusts are most numerous, whether by immi gration or otherwise, in warm, dry seasons. Cold and wet prevent hatching, and do great injury to the young that are hatched.