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THE CHIEF LossEs are occasioned in the Ohio and upper Mississippi valleys, and on the Atlantic coast highland. It does more damage to wheat than to any other crop, and the average annual loss is about 5 per cent of the crop. In years when the chinch bugs were unusually severe, the damage to wheat in single states has been estimated to be from ten to twenty million dollars. The losses are great because of the wide distribution of the pest, its prevalence to some extent every year, and its enormous multiplication in favorable seasons.
REMEDIES.—(1) Burning over the land; especially should this be done on waste and grass lands, and all rubbish should be burned. Grass is not injured by being burned over after the ground is frozen. It has been thought that the chinch bug was kept in check by the annual prairie fires in the early years of our country, the hibernating bugs being thus killed. Chinch bugs and other insects injurious to growing grain are practically unknown on the Pacific coast, where the large wheat fields are regularly burned over every year by burning the straw. (2) Trap or decoy crops, such as millet or Hungarian grass; these should be plowed under. When the young insects hatch, they easily reach the surface, but will perish if no crops are near. (3) Rotation; this involves a system disassociating small grains from corn. (4) Plowing; deeply plowing under the bugs collected on the edge of a field is helpful. (5) Spraying; the edge of the field infested may be sprayed with a very strong oily insecticide, even if the crop is killed with the bugs. (6) Protecting furrows. (7) Coal-tar barriers. (8) Artificial spreading of parasitic fungi; considerable work has been done in this line, with the conclusion that it is of little value. The bug is practically exterminated for the season, however, by wet weather and various fungous diseases which this causes. (9) Many bugs are also destroyed by birds, especially quails.”
The Wheat Midge (Diplosis tritici Kirby) belongs to the same order of insects as the Hessian fly, but in appearance and habit it is entirely distinct. It is believed to be identical with the notorious wheat midge of Europe, and it may also have been introduced into America in straw. It probably appeared first in Quebec, and has now spread throughout the Mississippi valley. The injury is inflicted by its orange-yellow larvae which extract the milky juice from the embryos forming in the wheat heads, thus causing the grain to shrivel and the heads to blight. In cases of unusual outbreaks the average losses of whole states have been from two-thirds to three-fourths of the entire yield. The wheat midge oviposits directly in the wheat head. The eggs hatch in about a week, and the larvae enter the kernel at once. They have extraordinary vitality, thrive best in moist weather, and winter in the ground, which they enter about three weeks after hatching. Plowing old wheat
1 Yearbook U. S. Dept. Agr., 1904, p. 466. * Webster, The Chinch Bug; Howard, The Chinch Bug.
fields deeply, burning the chaff and screenings of wheat from infested fields, and rotating crops are preventives. The Wheat Plant Lice cause injury by sucking their food from the soft, forming kernels. The yield may be reduced by as much as one-half, but extensive damage rarely occurs. The annual loss is thought to be at least 2 per cent. Locusts or Grasshoppers.-The locust, formerly present in some years in such overwhelming numbers that large swarms devastated extensive areas of all vegetation, has during the last decade ceased to be of such great economic importance. Locust plagues seem to occur occasionally on all of the continents, and do not seem to be limited to comparatively newly settled
regions. From 1889 to 1897 they wrought frightful havoc in Argentina, visiting 347,000,000 acres in the latter year, and destroying 30 per cent of the crops. From 1897 to 1900 the Argentine government spent over $7,000,000 in an attempt to exterminate them. The limit of the invaded region was steadily pushed northward, until in 1901 locusts were entirely absent from the wheat area. They came into Argentina from Bolivia, the territory of the Chaco, and western Brazil. Barcelona, Spain, reported a plague of locusts spreading in 1902. In west central Asia, between Askabad and Krasnovodsk, the cereal and cotton crops are commonly devastated by locusts. In 1903, 50,000 roubles were set aside to be devoted to the destruction of the insects’ eggs in trans-Caspia. It is claimed that sacked flour piled on open railway trucks near Krasnovodsk was devoured by clouds of rapacious locusts in an incredibly short time." In the United States during the early seventies the grass
hoppers used to invade Kansas “so they would block railroad trains and destroy all vegetation.’’” In the Red river valley they appeared in great clouds which “cleaned the country quite thoroughly on their flight.” These invasions seem to have come mainly from the permanent breeding grounds of the Rocky Mountain locust (Caloptenus spretus Uhler). These grounds were located approximately between the meridians of 102 and 112 degrees, and between the 40th and 55th parallels. 1 Mo. Sum. Commerce and Finance, Feb., 1904, p. 2818.
* Industrial Commission, 10:759. * Proc. Tri-State Grain Growers' Ass'n, 1900, p. 184.
East of this territory was a frequently invaded strip about five degrees in width. A great scope of territory farther east, south and west was periodically visited when the natural conditions on the permanent breeding grounds were such as to produce myriads of grasshoppers. They could live only one generation on the lower lands, and then perished. Large portions of their grounds are now cultivated, and this restricts their multiplication. It is thus perhaps impossible for such overwhelming swarms to occur as formerly. Such swarms as do occasionally appear are more localized, and not of such uncontrollable magnitude. They may still be relatively abundant, however. During 1901 in Canada, several hundred insects could be seen “to the yard,” and ‘‘dead locusts could be gathered up in wagon loads and at times be smelt for half a mile,” after poison had been used. In Montana they frequently devastate ranges so that the herds must seek pasture elsewhere. The Rocky Mountain Locust lays its eggs in almost any kind of soil, preferably in bare, sandy places on high and dry ground. They are laid chiefly in the first inch of soil, and in masses or pods surrounded by a mucous fluid, each pod containing about 30 eggs. The average laying season extends over 6 to 10 weeks, and about 3 egg masses are formed by each female. The time of hatching depends entirely on the climate and latitude. While the young locust is very active, it will remain almost stationary if food is plenty. The migrating propensity is developed only after the first molt, and frequently not until after the second or third. When food becomes scarce the locusts migrate, often in a body a mile wide. From the very first they conRocky MoUNTAIN Grass- Boo" and display gregarious inHOPPER; a, PUPA; b, FULL stincts. They feed as they advance, GROWN LARVA; c, YoUNG devouring everything in their path. LARVA. NATURAL SIZE. f they are numerous enough to devastate a region, they are forced to feed upon one another, and immense numbers perish from debility and starvation. They usually move only during the warmer hours of the day, and in no particular
direction, but purely in search of food. They generally march for one day, however, in the direction begun. If the vanguard does change its course, the new direction seems to be communicated in some way to those in the rear, which follow in wave-like form. There sometimes occurs the singular spectacle of two schools crossing each other, the individuals of each keeping to their own course. Some remarkable records have been made of phenomena resulting from the encountering of obstacles to the march. In Europe Döngingk claims to have seen them cross the Dniester for over one German mile, and in layers 7 or 8 inches thick. “In 1875, near Lane, Kansas, they crossed the Pottawatomie Creek, which is about 4 rods wide, by millions; while the Big and Little Blues, tributaries of the Missouri, near Independence, the one about 100 feet wide at its mouth and the other not so wide, were crossed at numerous places by the moving armies, which would march down to the water’s edge and commence jumping in, one upon another, till they would pontoon the stream, so as to effect a crossing. Two of these mighty armies also met, one moving east and the other west, on the river bluff, in the same locality, and each turning their course north and down the bluff, and coming to a perpendicular ledge of rock 25 to 30 feet high, passed over in a sheet apparently 6 or 7 inches thick, and causing a roaring noise similar to a cataract of water.’’’ Their unfledged existence terminates in about 7 weeks. During this time, even without change of direction, they could not travel over 30 miles. The swarms of winged insects will perhaps cover over an average advance of 20 miles a day. They spread most rapidly 4 or 5 days after they become winged, when, with a strong and favorable wind, they may reach a maximum of from 200 to 300 miles a day, and 50 miles per hour. The swarms generally move toward the south and southeast. This locust is single-brooded, dies with the approach of cold weather, and normally hibernates in the egg state. Other kinds of destructive locusts occur, as lesser migratory, non-migratory, redlegged, California devastating, differential, two-striped, pellucid, and American Acridium, but the damage occasioned by these has never been comparable to that caused by the Rocky Mountain species. 1 U. S. Dept. Agr., Div. of Entomol., Bul. 25, pp. 21-22.