from issue: 43-2
In Relation to Cereal and Forage Crops
Information gleaned from USDA Farmers’ Bulletin No. 747
We have been highlighting the importance of insects and it therefore may seem contradictory to include this article talking about the damage grasshoppers sometimes do to farmer’s yields. While grasshoppers can do significant damage to our crops, without these insects the ecosystem would be a much different place. Along with other insects, they play a critical role in the environment, benefiting the lives of other plants and animals.
According to Seth Zawila in, “What is the Grasshopper’s Job?”, they fertilize the soil by consuming two times their weight a day in food and leaving their exoskeletons behind which have valuable minerals for the soil. They are also a staple food source for birds, mice, and other predatory insects. The fact that they eat through excess weed plants is the main reason they are viewed as more harmful than beneficial in farm fields where one plant is the dominate species, but when our fields are full of diversified plants, weeds, and crops, this becomes less of a problem. – SB
PRINCIPAL KINDS OF GRASSHOPPERS INVOLVED
Many kinds of grasshoppers eat grains, grasses, and forage crops throughout the United States. The more important are the differential (Melanoplus differentialis Thom.), the two-striped (Melanoplus bivittatis Say.), the Carolina (Dissosteira carolina L.), the lessor migratory (Melanoplus atlanis Riley.), the pellucid or clear-winged (Camnula pellucida Scudd.), the red-legged (Melanoplus femurrubrum De G.), the California devastating (Melanoplus devastator Scudd.), the southwestern lubber (Brachystola magna Gir.), the Florida lubber (Dictyophorus reticulatus Thunb.), and the New Mexico long-winged grasshopper (Dissosteira longipennis Thom.).
In the following pages is given a short description of these grasshoppers and the regions in which they occur, together with their life history, the crops eaten, and measures for controlling them.
The southwestern lubber grasshopper (fig. 1), a very large species, lives in the semiarid regions of the Southwest. It is usually pale green in color, speckled and marked with pink and brown, and is wingless throughout its entire life. It sometimes becomes injuriously abundant on the cattle ranges and dry farms of New Mexico and Arizona, but is found throughout the Great Plains region from Wyoming and South Dakota to New Mexico and Texas. It is known to eat corn, kafir, alfalfa, and grasses of various kinds.
The Florida lubber grasshopper (fig. 2) is a clumsy insect, often reaching the length of more than 2-1/2 inches, and is correspondingly robust. It is usually yellowish in color, prettily marked with black, and its short and nearly useless wings are more or less distinctly stained with a bright crimson color. It inhabits the southern United States from North Carolina to Texas and has been especially injurious throughout the newly reclaimed regions in the State of Florida. It has been found to eat corn, grasses, sorghum, cowpeas, soy beans, and other crops.
The differential grasshopper (fig. 3) is usually a yellowish-colored insect with clear glassy hind wings, averaging nearly 1-1/2 inches in length. Its hind legs are usually distinctly marked with yellow and black, the colors arranged in chevron-shaped bars on the sides of the thighs. It is found throughout nearly the entire United States, although of rare occurrence in the Atlantic States. This grasshopper is chiefly injurious in the middle western and southwestern States, and is known to eat the following cereal and forage crops: Corn, sorghum, oats, wheat, bluegrass, soy beans, clover, and alfalfa.
The two-striped grasshopper (fig. 4) is a compact, yellowish species, bearing, as it name implies, two yellow stripes running from the forehead down each side of the otherwise brown back. It varies from 1 to 1-1/2 inches in length and its hind wings are nearly colorless. This species is found from southern Canada to Mexico, excepting the South Atlantic States, and eats wheat, corn, grasses, alfalfa, and clover.
The lessor migratory grasshopper (fig. 5) is a rather small, yellowish-gray species, averaging about 1 inch in length and bearing a distinct patch of black on the neck or collar. Although this grasshopper is comparatively small in size, it is a strong flier and eats alfalfa, grasses, timothy, corn, rye, soy beans, and wheat. It is found throughout nearly the entire United States, but is chiefly injurious in States west of the Mississippi River.
The red-legged grasshopper (fig. 6) is one of the most widely distributed of the species discussed. It is a small, yellowish insect, having its legs partly tinged with a bright reddish hue. Its back is brownish and the hind wings are colorless. It is found in considerable numbers throughout the entire United States, southern Canada, and northern Mexico, and is known to eat wheat, corn, bluegrass, oats, rye, timothy, and soy beans.
The California devastating grasshopper (fig. 7) is a rather small species resembling somewhat the common red-legged grasshopper, but its injurious work is confined to the western United States, and especially California, where it frequently eats alfalfa.
The Carolina grasshopper (fig. 8) is of moderate to rather large size, and is usually of a plain pepper-and-salt color, sometimes varying, in accordance with the soil upon which it is found, from gray through yellowish to a distinctly reddish color. Its hind wings are nearly black but are margined with yellow. Thus it is rendered inconspicuous while sitting upon the ground but catches the eye immediately upon taking flight. It is very widely distributed throughout the entire United States and is known to eat corn, wheat, alfalfa, and soy beans.
The pellucid or clear-winged grasshopper (fig. 9) is a small species having its hind, or true, wings clear or pellucid, while the front wings are distinctly blotched with brown. It is at times one of the most injurious species found within the limits of the United States. It has been especially injurious in the States of Idaho, Utah, and California, but is also found in Arizona and New Mexico. It is distributed throughout the northern United States from the Atlantic to the Pacific. This grasshopper is known to eat oats, wheat, grasses, and occasionally flax.
The New Mexico long-winged grasshopper (fig. 10) is a large, strong-flying species, often measuring more than 2 inches in length and is yellowish-gray, marked with chocolate-colored spots. It is known to exist in the central United States, from Idaho and Montana to New Mexico and Texas, and eats the native grasses on the cattle ranges of New Mexico.
MANNER OF INJURY
Grasshoppers, both young and old, injure crops in but one way, that is, by gnawing and devouring them wholesale, and where very numerous they have been known to consume almost every green thing in sight. Even the bark on the tender twigs of trees is eaten by these ravenous insects, which are known to gnaw the handles of agricultural tools, such as hoes and rakes, in order to secure the salt left upon them by the perspiring hands of the farmer.
CONDITIONS FAVORABLE TO OUTBREAKS OF GRASSHOPPERS
It is generally believed in the middle and far western regions of the United States that when two dry summers occur in succession, the second one usually produces serious outbreaks of grasshoppers. Whether or not this be true, there is ample evidence to show that dry weather favors the successful hatching of the eggs and their subsequent development. On the other hand, cool wet weather is unfavorable, and grasshoppers often die in great numbers from disease when such weather conditions prevail.
LIFE HISTORIES AND DEVELOPMENT OF GRASSHOPPERS IN GENERAL
The life histories of the various species of grasshoppers are quite similar in character. The eggs are usually deposited in the soil, inclosed in sacs, or “pods” (fig. 11), formed of a glutinous substance furnished by the female. The grasshopper thrusts her tail or abdomen, which is capable of considerable extension, into the soil (fig. 12) and starts laying her eggs at the farther end of the tunnel thus formed, which is then filled with eggs and afterwards sealed. One grasshopper sometimes deposits a great many eggs. In the semiarid portions of the country, where the soil frequently becomes baked and hardened by the sun, the eggs are often laid in great numbers in the crown of plants such as alfalfa, and in California as many as 2,000 eggs have been found in the crown of a single alfalfa plant.
The banks of irrigation canals are favorite egg-laying grounds for grasshoppers (fig. 13). In New Mexico and Arizona the eggs frequently are laid in the bottoms of shallow arroyos where they are inaccessible to cultivating implements. The waste lands of Idaho, Washington, and some other Northwestern States afford other instances where the destruction of grasshopper eggs in not practicable on a commercial scale.
The egg laying usually takes place in late summer or early fall and the young grasshoppers emerge the following spring. In some of the Southern and Southwestern States the young grasshoppers may emerge as early as February. In the North the eggs usually do not hatch until some time during the months of May or June.
In contrast with many other insects, grasshoppers when hatched closely resemble their parents, excepting their lack of wings (fig. 14). There is no grub-like larval stage nor is there any resting or true pupal stage such as is the case with butterflies and moths. The young grasshoppers are active and able to hop almost immediately upon emergence from the eggs. It takes from 70 to 90 days for the young grasshoppers to grow to maturity and develop wings. When the grasshopper reaches a certain stage of development its skin splits and is shed, the insect usually acquiring wings during the operation. It has then reached its final stage of growth and is ready to mate and reproduce its kind. So far as known grasshoppers have only one generation a year.
NATURAL ENEMIES OF GRASSHOPPERS
Several kinds of parasitic two-winged flies deposit their eggs or maggots upon grasshoppers in their mature or nearly mature stage. Among the most important of these is a blowfly or meat fly (fig. 15), which has been observed to deposit live maggots upon the wings of the grasshoppers while they are in flight. The maggot of this parasite devours the internal portions of the grasshopper’s body and soon causes its death. Robber flies (fig. 16) feed very largely upon young grasshoppers, grasping them in their long, stout legs, thrusting the strong beak through the body wall of the grasshopper and sucking out the liquid contents of the body. Several kinds of digger wasps (fig. 17) kill or stupefy grasshoppers by stinging, and then drag them into their underground nests, after which the wasp lays an egg upon the body of the grasshopper, which subsequently becomes food for the newly hatched grub. A number of blister beetles are known to prey in their younger stages upon the eggs of grasshoppers, but as the adult beetles sometimes eat potatoes, beans, and other cultivated plants, they can not be considered as entirely desirable allies of the farmer.
WILD AND DOMESTIC BIRD ENEMIES
The Bureau of Biological Survey has found that wild birds play a great part in the natural control of grasshoppers. These feathered friends of man are always present where grasshoppers abound and work almost constantly in aiding the farmer. The statement that all birds feed upon grasshoppers is so near the absolute truth that it needs only insignificant modifications. From the largest hawks to the tiniest hummingbirds there are no exceptions other than the strictly vegetarian doves and pigeons. Although birds of all families prey upon grasshoppers, the following may be selected as the most important eaters of grasshoppers for their respective groups: Franklin’s gull, bobwhite, prairie chicken, red-tailed, red-shouldered, broad-winged, and sparrow hawks, the screech and burrowing owls, yellow-billed cuckoo, road-runner, nighthawk, red-headed woodpecker, kingbird, horned lark, crow, magpie, red-winged and crow blackbirds, meadowlark, lark bunting, grasshopper and lark sparrow, butcher bird, wren, and robin.
Domestic fowls are also very fond of grasshoppers and feed greedily upon them whenever possible. Turkeys are sometimes killed by eating too freely of grasshoppers, the strong, rough hind legs of which cause severe lacerations or even puncturing the crops of the birds.
There exists ample evidence showing that grasshoppers, or locusts, as they are most often called in the Old World, have been reckoned among the principal insect enemies of agriculture since man began to till the soil. The writings of Egyptians, Greeks, and ancient Hebrews all contain references to these insects as hateful pests of the farmer. In North America unmistakable representations of grasshoppers are found on pottery and in the picture writings of the prehistoric Indians and Aztecs. It is therefore quite probable that grasshoppers attacked the maize and other crops of the Indians long before the coming of the white man. The early history of the New England States affords numerous records of the inroads by grasshoppers upon the crops of the settlers. During the period 1743 to 1756 a great scourge of these hungry insects occurred in Maine, and other outbreaks occurred in Vermont during the year 1797 to 1798. When European agriculture began to be established generally in the Great Plains region of the United States, lying west of the Mississippi River and east of the Rocky Mountains, during the decade 1870-1880 a migratory species of grasshopper, commonly known as the Rocky Mountain locust (Melanoplus spretus Uhl.), frequently swooped down from its breeding grounds on the benches of the mountain range in such great swarms as to destroy practically all cultivated crops over vast areas of country. As the European settlement of the Rocky Mountain region progressed and the breeding grounds of this destructive insect came under the influences of cultivation these outbreaks ceased. Thus, there has not been a serious general outbreak of the Rocky Mountain locust since 1880, and this particular grasshopper has ceased to be a pest of any great importance.
However, there are many other kinds of grasshoppers having different habits which have since hampered the farmer and undoubtedly will continue to rob him of his crops for years to come unless persistent concerted action of agricultural communities in combating these pests succeeds in securing permanent relief.
There are three principal methods of control which have been found to be of greater or less practical value in combating grasshoppers in this country: First, the destruction of the eggs; second, catching the insects in the field by means of traps; and, third, the use of the poisoned baits. We will discuss here the first two methods.
DESTROYING THE EGGS OF GRASSHOPPERS
It is seldom practicable to destroy the eggs because of the many different hiding places chosen by the grasshoppers in laying them and the impossibility of reaching the same with cultivating implements. However, where they are accessible the ground containing them should be thoroughly plowed, or disked, and harrowed in the fall, as these operations prevent the eggs from hatching successfully the following spring. Attempts to reach the eggs by handwork, such as digging up the soil, is practicable only in gardens, truck farms, and places where intensive cultivation is practiced.
MECHANICAL MEANS OF DESTROYING GRASSHOPPERS
The most common method of destroying grasshoppers mechanically is by the use of a simple horse-propelled implement or trap commonly called a hopperdozer. These implements are constructed along similar lines, but are of many slightly different patterns. As originally built the hopperdozer consisted of a galvanized sheet-iron pan or trough having a back rising at right angles to the pan. It was about 16 feet in length and mounted on runners made of wood or old wagon tires. Most of the hopperdozers recently constructed have a pan made of galvanized sheet iron, but the back and side wings are usually built with a wooden frame covered with stout muslin or light cotton duck, thus securing lightness and elasticity of structure (fig. 18). An implement of this kind has been constructed recently with a back curving slightly forward (fig. 19). The back and sides of this implement are covered with tin, nailed to furring strips carried by the uprights of the frame. It has been used successfully in western States, and it is claimed that the slight curve of the back and the slippery surface of the tin aid in precipitating the grasshoppers into the pan. As many as 300 bushels of grasshoppers have been collected by the use of hopperdozers on 100 acres of alfalfa. But even where these implements may be used successfully, a great many grasshoppers escape being killed by them. The hopperdozers can not be used on uneven, stony, or recently cleared, stumpy ground, nor in meadows or fields of grain where the crops have reached a considerable height.