Grasshoppers

J. R. Parker.

Grasshoppers have caused concern among men since the beginning of recorded history. They have brought fear and famine at one time or another to every continent. A description of their ravages is given in Joel 2: 3 "The land is as the Garden of Eden before them, and behind them a desolate wilderness, yea, and nothing shall escape them."

Grasshoppers are recorded as having injured crops in New England in 1797. In 1818 hordes of them destroyed the crops of early settlers in the Red River Valley in Minnesota. During 1874 to 1877 the Rocky Mountain grasshopper, or locust, as it was then called, increased to such numbers that its depredations were considered a national calamity. Great swarms originating in the plains east of the Rocky Mountains in Montana, Wyoming, and Colorado migrated to the Mississippi Valley and Texas, devouring crops wherever they paused in their flights. Damage to crops amounted to 200 million dollars. Congress recognized the seriousness of the outbreak and on March 3, 1877, created the United States Entomological Commission and authorized it to investigate the grasshopper problem.

Grasshoppers still destroy crops somewhere every year and during outbreaks cause losses totaling millions of dollars. Overgrazing by grasshoppers is one of the fundamental reasons for loss of productive grasslands in many States. Grasshoppers contribute to soil erosion and dust-bowl conditions, particularly when drought and mismanagement of the land also occur.

Grasshoppers are found all over the United States, but serious outbreaks seldom develop in the East. Local outbreaks have occurred in New England, New York, Virginia, Georgia, Florida, Alabama, and Mississippi, and grasshoppers are numerous enough to cause some damage in most Eastern States every year. Outbreaks are mostly in the western two-thirds of the United States. They occur most frequently in the Northern Great Plains, including eastern Montana, North Dakota, South Dakota, Nebraska, and Kansas.

Every State within the region subject to outbreaks has more than 100 kinds of grasshoppers. Some are rare and others fairly common. Only a few ever become abundant enough to injure crops seriously. At least go percent of all grasshopper damage to crops is caused by five species, the lesser migratory grasshopper, the differential grasshopper, the two-striped grasshopper, the red-legged grasshopper, and the clear-winged grasshopper.

The lesser migratory grasshopper, the two-striped grasshopper, and the red-legged grasshopper are found throughout the grasshopper country. The differential grasshopper seldom moves farther north than the southern borders of North Dakota and Minnesota. The clear-winged grasshopper is confined largely to States bordering the Canadian boundary from Michigan to Washington, but in the mountainous West it extends south to New Mexico, Arizona, and southern California.

The lesser migratory hopper normally selects well-drained, light soil and sparse vegetation. The differential, two-striped, and red-legged grasshoppers prefer moist, heavy soil and lush vegetation. The clear-winged grasshopper adapts itself to many conditions but is most common in mountain meadows, grassy openings in timbered land, and well-sodded, closely grazed pastures on the open plains. Under outbreak conditions all five species spread far from favored habitats and feed on a variety of crops and vegetation.

Of the five species, the lesser migratory grasshopper is the most widely distributed and most destructive. It is a strong flier. Adults sometimes gather in great swarms, which migrate hundreds of miles and destroy crops and range plants wherever they pause in their flight. In most respects it resembles the Rocky Mountain locust, or grasshopper, which ravaged Western States years ago. The latter has longer wings and stronger power of flight, characteristics that several species are known to develop during periods of great abundance. It was called a locust because its habits were similar to those of Old World locusts.

In most parts of the world the word "locust," or its equivalent, designates grasshoppers that migrate in swarms the same species may be a grasshopper during its periods of small numbers and a locust when it becomes extremely abundant. Everyone understands the term "grasshopper" as commonly used in the United States. It is less confusing to use the term than to change to locust when the same grasshoppers fly in swarms. The periodical cicada and its relatives are popularly known as locusts. They are entirely different from grasshoppers in appearance and habits.

Of the 142 species collected on range plants in the Western States, only a few are known well enough to have common names. Considerable training in taxonomy is needed to identify the adults correctly. Often it is impossible to recognize the immature stages. On the basis of surveys and observations made in range districts since 1936, the most abundant species in Montana, North Dakota, South Dakota, Nebraska, and Wyoming have been Melanoplus mexicanus, Ageneotettix deorum, Amphitornus colossus, Phoetaliotes nebrascensis, M. angustipennis, Phlibostroma quadrimaculatum, O peia obscura, Trachyrhachis kiowa, M. infantills, Aulocara elliotti, M. gladstoni, Mermiria maculipennis, Cordillacris occipitalis, Melanoplus femur-rubrum, Encoptolophus sordidus, Metator pardalinus, and Drepanopterna femoratum.

Mention also should be made of the long-winged plains grasshopper and Melanoplus rugglesi, both of which are migratory and highly destructive during outbreaks. The adults fly in swarms and oviposit in well-defined egg beds. The young hoppers march in bands.

Grasshopper.

Outbreaks of the long-winged plains grasshopper have occurred in Colorado, New Mexico, Oklahoma, Texas, and western Kansas. Outbreaks of M. rugglesi have occurred in Nevada, southeastern Oregon, and northeastern California. The Mormon cricket, a long-horned grasshopper or katydid, should also be listed as a pest in the Rocky Mountain and Plateau States. It is normally confined to range vegetation in foothills or mountains, but large bands sometimes migrate long distances and attack crops.

WITHIN THE REGIONS where conditions are most favorable for grasshoppers are the principal wheat, barley, and flax areas in the United States. In them also are extensive acreages of corn, oats, rye, and alfalfa. Grasshoppers relish all those crops.

Damage even in average years is more serious than most of us realize. The grasshoppers may eat only a small part of the host plants, but they attack them at vulnerable points. They bite off grain heads and flax bolls and may injure the rest of the plant only slightly. They go for corn silks; if the silks are eaten in the early stage, pollination is prevented and the ears do not fill. Grasshoppers prefer the flowers of alfalfa and sweetclover to the foliage, and heavy losses consequently befall beekeepers and seed growers. Small numbers of hoppers can greatly reduce cotton yields by cutting the seedlings and later the bolls.

Damage in outbreak years has varied from partial to complete destruction of crops over large areas. Estimates by entomologists and county agents in 23 States put the total of losses at $789,374,140 in the 25 years between 1925 and 1949.

The Forest Service reported that in 1934 grasshopper damage to range vegetation in Colorado, Montana, Nebraska, North Dakota, South Dakota, and Wyoming amounted to $2,455,000. Similar damage continued in 1935. In 1936 the Wyoming State. entomologist estimated grasshopper damage to forage in Wyoming at $1,480,351. The figures cover only the normal annual value of the forage and do not include such indirect losses as the forced sale of unfattened animals and breeding livestock. As I said before, overeating of grasslands by grasshoppers, particularly in drought years, hastens soil erosion. Reseeding is prevented, vegetative cover often is completely removed, and the soil is exposed to washing and blowing. Areas so affected for several seasons may remain depleted for years.

The division of cereal and forage insect investigations is responsible for grasshopper research conducted by the Bureau of Entomology and Plant Quarantine. Most of the work is centered in its field station at Bozeman, Mont. Staff members of the station study grasshoppers in many States, but most of their work is done in Montana, North Dakota, South Dakota, and Wyoming, where grasshoppers are a serious problem nearly every year.

RESEARCH ON GRASSHOPPERS also is carried on at other field stations of the Bureau. Stations at Manhattan, Kans., Sacramento, Calif., and Forest Grove, Oreg., have included grasshopper investigations in their work programs. In 1950 work on grasshoppers was done at Tempe, Ariz., and Tifton, Ga. Staff members of the Tempe station test new insecticides and carry on field research during the long period of grasshopper activity that prevails in Arizona, March to December.

The research has two main aspects. One has to do with the recognition, distribution, seasonal development, and habits of grasshoppers, and with ecological studies the effects of meteorological factors and natural enemies upon their abundance. The second division pertains to the immediate control of grasshoppers by insecticides, cultural methods,or other means. These are termed control investigations. No clear-cut distinction actually exists between the two aspects. The objectives are the same, and one depends on the other.

Permanent study areas were established in Arizona, California, Kansas, Minnesota, Montana, North Dakota, and South Dakota, beginning in 1936. Each area included at least 8 square miles of typical farm land. All had histories of grasshopper outbreaks. Maps were made to show the locations of crops, idle land, and native vegetation. Air and soil temperatures and precipitation records were kept. Annual adult, egg, and nymphal surveys were made on each quarter section for 10 years.

The studies produced data on the seasonal development, preferred habitats, food preference, egg-laying habits, and population records of grasshoppers. Information on the effects of parasites, predators, disease, and meteorological factors also was obtained. I cite some of the findings.