The GRASSHOPPER Your SHARECROPPER
R. L. Shotwell Entomologist
BULLETIN 714 OCTOBER, 1958 UNIVERSITY OF MISSOURI AGRiCuLTURAL EXPERIMENT STATION COl'f" /'/)(JI()l!.""jih, (oIlYleJ)' Dr. Roberl E. Pj~tdl , I:ntlllll{)/()gy Dejll .. ( 'lIil'enil)' IJ/ WY{)lIIilll!..
CONTENTS
Grasshoppers in Missouri History ...... 3
Grasshoppers as Food for Humans . . . . 5
Kinds of Grasshoppers . . . . 6
The Important Missouri Grasshoppers . . . . 7
Life Story of the Grasshopper 8
How Grasshoppers Live . . . 11
Control of Grasshoppers . . 13
Thi.r Imllelin reporlJ on Deptl r/ fllml of En tolllology re.reclt'Ch project 286, COni GraJJho/Jper.1. The alllh()r, R. L. Shotwell, Entolllologi.rl with the Enlomology Re.rea rch DilliJio17 , AgriCllltll rct/ l?.eJearch Service, U. S. Dep(/ rllllm i of .I1griCIIllll re, worked in cooj)(!rrJ /i()/'/ ll'ith the Unil)enily 0/ Mir .rollri AgriCIIllllrci/ E.\perimenl SlalirHl Clnd AgriC/lltll ral ExtellJiol7 Sen/ire.
Nymphs of the differential grasshopper attacking corn plants. The GRASSHOPPER ... Your SHARECROPPER
R. L. Shotwell, Entomologist
lIThe land is as a garden of Eden before them, and behind them a desolate wilderness; yea and nothing shall escape them." Joel II:3.
GRASSHOPPERS IN MISSOURI HISTORY
Grasshoppers have periodically shared large por migrated into western Missouri during four periods, tions of our crops since Missouri became a state in 1818-20, 1855-57, 1866-68, and 1873-76. 1821. Some 45 of Missouri's 137 years of statehood The State entomologist for Missouri, C. V. could be called grasshopper years - years in which Riley, writing in 1877, said: 2 grasshopper damage to crops was either locally or generally severe. "The voracity of these insects can hardly be imagined by those who have not witnessed Early Outbreaks them in solid phalanx falling upon a corn field and converting in a few hours the green The earliest outbreaks in Missouri were caused and promising acres into a desolate stretch of by the famed Rocky Mountain grasshopper. 1 The bare, spindling stalks and stubs. Covering each hill by hundreds; scrambling from row permanent breeding grounds of this grasshopper to row like a lot of young famished pigs let were in the prairies just east of the Rockies in out to their trough; insignificant individually north-central Wyoming, central and northern Mon but mighty collectively-they sweep clean a tana, and southern Alberta and Saskatchewan. His field quicker than a whole herd of hungry tory records that in some years great swarms flew steers. Imagine hundreds of square miles ou t of their breeding grounds into Minnesota, Iowa, covered with such a ravenous horde and one can get some realization of the picture pre and Missouri and south through Texas as far as the sented in many parts of the country." Gulf of Mexico. Between 1818 and 1876 swarms 2Riley, C. V., The Locust Plague in the United States. Rand, 1 Melanoplus spretus. McNally Co., Chicago Publishers, 1877. A Governor's Proclamation
At one time the: pcoplt.: believed these plagues ro be ".I n eXI ress i"n o( Di\ ii1t: wrath tor the sin Today, this would include about all of the state east of H ig hway 65 from Springfield Outbreaks Since 1876 through C hillicothe. G rass hopper outbreaks in Missouri since 1876 Riley gave two reasons for his prediction whid1 have been attributed to native grass hoppers. At first are important tOday in the geographical distribution it was believed that with the end of the great mi and development of grass hopper infestations_ First, gratory swarms, the Rocky Mountain grass hopper thi ~ eastern limit of fli g ht was approximately on a had disappeared from the Face of the earth. T here is -4- The riddled, leafless cornfield is a common sight during bad grasshopper years. now ev id ence th at thi s g rass hopper was a mi gratory north wes tern qu arrer of rh e state. In oth cr wo rds, the phase o f the spe ies now kn wn as the mi gratory worsr infes tati ons we re limited to thar part of thc g rass hoPI er. This spec ies is co mm on over mos t of state beyo nd whi h Riley sa id th e Roc ky Mountain th e inl abitable North Ameri can co ntinent, but on grass hopper wo uld not sprea d beca use c nditions ditions for th e developm ent of such grea t migratory were not favorable for its develo pm ent. In the swa rm s have changed. Since 1876 large porti ons of United tates, gra ss hoppers beco me more and more th e grea t plain s region, in clu din g rh e breeding of an annual probl 'm as one leaves th e regions of a grounds, have been di vid ed into farm s and th e native 30-in ch or grearer annual rainfall and progresses west sodland has bee n broken up in ro cultiva ted field s. through regions hav ing 20 to 10 in ches. The g rass hoppers n lo nge r nee d leave home in The last two severe outbrea ks in Mi ssouri occur sea rch of food. red in rh e 1930's and rhe 1950'5. Ir is sign ifica nr th at There were a number of years between 1876 and seven of the ten yea rs beginning in 193 1 we re dty 1957 when native g rass hoppers rea hed outbreak years and fi ve of the six yea rs beginning in 195 1 were proporci ons in Mi sso uri. Severe infes tati ons occurred also mu ch below norm al in rainfall. in the wes tern hal f a nd the mos t severe ones in the GRASSHOPPERS AS FOOD FOR HUMANS During the severe g rass h pper plagues in the of its norm al food suppl y by these sa me in se ts. 1870's, grasshoppers were tested for their palatabili ty For ce nturies grass hoppe r have been used as fo od and value as food for humans in a country ravaged by peo pl e in rmny partS of th e wo rld. Within the -5- last few years in the United States canned grass "It was most amusing to note how, as hoppers ha~e been on the shelves of grocery stores the rather savory and pleasant odor went up selling exotic foods. from the cooking dishes, the expression of horror and disgust gradually vanished from In Missouri in 1875 Riley investigated the pos the faces of the curious lookers on and how at sibility of using grasshoppers for food. He went so last the head cook took part in the opera far as to go on a strict grasshopper diet. He gave tions; how when the different dishes were this as his reason: neatly served upon the tables and were freely partaken of with evident relish and many ex "I was governed by weightier reasons ' pressions of surprise and satisfaction by the than mere curiosity, for many a family in ladies and gentlemen interested, this same Kansas and Nebraska were brought to the cook was actually induced to try them and brink of the grave by sheer lack of food while. soon grew eloquent in their favor; how the St. Louis papers reported cases of actual finally a prominent banker as also one of the death from starvation in some sections of editors in town joined in the meal. The soup Missouri where the insects abounded and ate soon vanished and banished silly prejudice; up every green thing in the spring of 1875." then cakes with batter enough to hold the "Whenever the occasion presented I locusts together disappeared and were pro partook of locusts [grasshoppers) prepared in nounced good; then baked locusts with or different ways and one day ate of no other without condiments; and when the meal was kind of food, and must have consumed, in completed with dessert of baked locusts and one way and another the substance of several honey a la John the Baptist, the opinion was thousand half grown locusts." unanimous that that distinguished prophet no longer deserved our sympathy and that he He was agreeably surprised after some misgiv had not fared badly in the wilderness." ings that they were quite palatable. "Fried or roasted in nothing but their own oil with the addition of a Several others at Riley's suggestion experimented little salt and they were by no means unpleasant eat in preparing grasshoppers for their own consump ing and have quite a nutty flavor." tion and said they were excellent. Evidently the idea At one hotel he finally succeeded in getting the did not catch on, because there are no recipes in our cook to let him prepare a complete meal using grass cookbooks for preparing grasshoppers baked, fried hoppers. or stewed. KINDS OF GRASSHOPPERS Four Important in Missouri Grasshoppers belong to the family Acrididae of red-legged grasshopper. 6 All four belong to the sub the order of insects called the Orthoptera. Other family Cyrtacanthacridinae, or spine-breasted grass members of this order are the crickets, cockroaches, hopper. Beneath the body between the front pair of and katydids. In Missouri one could easily collect 30 legs is a distinct spine. to 40 different kinds of grasshoppers, all of which cause some damage to our native and cultivated The Less Important Species plants, but from an economic standpoint there are In our pastures and sometimes in our crops we only four kinds considered important. They are the have two other groups which we could call the migratory grasshopper, 3 the differential or big yellow musical or noise making grasshoppers. The males grasshopper,4 the two-striped grasshopper,5 and the alone have the musical organs. This caused some- 3 Melanoplus bilituratus. 5 M. bivittatus. 4M. differentialis. 6 M . femur-rubrum. -6- one to say: or red with some black. In flight they can be mis taken for butterflies. Some of the species of band "Happy the grasshopper lives Since they aJl have noiseless wives." winged grasshoppers are of great economic impor tance in the rangelands of the West. There the con One of these musical groups is the subfamily ditions, drier than those found in Missouri, favor Acridinae, or slantfaced grasshoppers. From the top their development. of the head the face is slanted backwards, often mak Our most common band-winged form is the 7 ing the head cone-shaped. They are the grasshoppers Carolina grasshopper. It is a rather large, long you often hear making stridulating sounds or a winged grasshopper, whose general color is a dull shrill buzz. They do this by rubbing the inner part ashy-brown sprinkled with numerous small dusky of the hind legs against the fore wing. Quite often spots. It is the most noticeable because it congre one or two species of this family will occur in suf gates along roadways and paths rather than in fields ficient numbers to do severe damage to our pasture or pastures. This gives an exaggerated impression of grasses. their numbers. You may think there is a damaging The subfamily name of the other musical group infestation of grasshoppers when that is not so. Be is Oedipodinae or band-winged grasshoppers. Most cause of its conspicuous black wings and habit of of these make a harsh, crackling or rattling sound in frequenting roadsides, this is one of the best known flight which is as characteristic of a summer day as of our Missouri grasshoppers although it is not of the flight of a butterfly. They make this noise by much economic importance. rubbing their wings together. Most of the species of ; Dis.rosteira carolina. Oedipodinae have inner wings colored mostly yellow THE IMPORTANT MISSOURI GRASSHOPPERS The migratory grasshopper is about one inch Before the midweStern and plains states were set long. The body is grayish or reddish brown with ir tled, the differential grasshopper lived in the weedy regular black markings just back of the head. Its creek and river bottoms. After such crops as small favored breeding places are pastures, grain stubble, grains, corn, and alfalfa covered the prairies, it moved and poor stands of alfalfa and clover. Of the four into the croplands. There it found ideal breeding species important in Missouri it is the first to appear places in field margins, closely grazed pastures, and in the spring. It is a strong flier and has. been known poor alfalfa stands, together with an abundant food to migrate 200 to 300 miles in a single season. In supply in the nearest crops. In the Corn Belt where the country as a whole it has caused more crop it became a number-one threat to the corn, in many damage than any of the other grasshoppers. places it has rightly earned the name of "corn hop The diffirential, or big yellow,·grasshopper is per." It is also a strong flier, but not the long-dis a robust insect about 11;2 inches long, the females tance flier that the migratory grasshopper is. During larger than the males. The body is a dark brownlsh the recent outbreaks in Missouri, the differential and green or olive-brown above to a dull or bright yel migratory grasshoppers were by far the most im low beneath. The hind thigh is dull to bright yellow portant species. in color, and bears narrow black bars arranged in The two-striped grasshopper is about 1 ~ inches herring-bone fashion, resembling chevrons. This long. The females are larger than the males. You species appears about the middle of May, three weeks may easily recognize this species by the two yellow later than the migratory grasshopper. ish stripes, which gave it its name, extending from -7- the eyes on the sides of the head back almost to the The red-legged grasshopper gets its name from tips of the wings. The body is olive-brown above to its reddish hind legs. The body is reddish brown a pafe to dull greenish yellow beneath. It breeds in above and a dull greenish to sulfur-yellow beneath. It pastures, field margins, and wherever there is open, is about the size of the migratory grasshoPFer. The weedy or soddy ground. Like the migratory grass females of the two species can hardly be distinguish hopper, it hatches early, and often occurs in damag ed. It is found in various habitats, but particularly ing numbers. In Missouri, however, it has not equal in pastures and alfalfa fields. In some sections of the ed the migratory or differential grasshoppers in country where alfalfa is the important crop, it is the economic importance. number one grasshopper. LIFE STORY OF THE GRASSHOPPER Egg Laying Of the four important species in Missouri, only the migratory grasshopper is known to have two generations in a single season, with eggs for the sec ond generation deposited in June and early July. All four species lay eggs in the late summer and fall. These overwinter in the soil and hatch the follow ing spring. Different species select different places for egg laying, but the method for depositing eggs is similar for all. The female presses the tip of her abdomen against the soil surface and digs her way down by means of a horned process at the end of her body (Fig. 1, Fig. 2), and then deposits one egg at a time until for most species 15 to 100 of them are placed in regular order. Fig. 2-Last abdominal segments showing the differ ence between male and female grasshoppers. Adult two striped grasshoppers used to illustrate. Top and side views of female above, top and side views of male below. Migratory and red-legged grasshoppers will de posit about 20 eggs in a mass while the differential and two-striped grasshoppers will place 50 to 100 eggs in a single mass. The migratory grasshopper, although laying. fewer eggs per mass, can lay up to 15 to 20 masses. The differential and two-striped grasshoppers lay three to four pods. Studies of mass egg laying have shown that each female lays about Fig. I-Female two-striped grasshopper laying eggs. 300 eggs. -8- ,Ire ue:1m-co lon:d or whiti sh and II " in ch in length. T he eggs of all tOLlr species arc hanana-li ke in shape. A II or rhese spec ie ~ avoid loose so il when lay ing eggs, preferring firml" packed ground. T he egg pods of th e two-striped and differential grass hoppers :Ire co nce nrrared among the roOtS of sca nned g ra ss clumps and weeds along roadsides, in field marg ins, in pastures, poorer stands of :d f: d fa and clover, com and so rgh um fields , and so metim es among the roots of the co rn plants th emse lves. Eggs of the migratory g rass hopper arc more scarrned and :lI'e found th roughou t past ures, in bare spotS in poorer s t ~ nels uf :tlfalfa, or in small -g rain st ubble fie ld s clin g ing m til e rootS of th e stubble or nea rb y in Spo tS where Fig . 3- Egg pods of two-s triped grasshopper, natural [il e dirt is firml y packed , Pods o( th e red-Ieggccl size. g rass hopper arc (ound sclttcred in all of rhe loca rions sci e([ed by the \ ther th ree species. Somctimes A g lu ey fluid is di sc harged along with the egg~. .t (emale may be forced to d epo~i t eggs in less desir mi xing with th e surrounding so il. The holt is also ;tbl · "l aces. capped with rhi s fluid and the whole mas s hardens In bulletins on gra ss hopper control, we arc into a pod (F ig. 3). This ce menting process pro teLTs urgecl [ 0 kill the grass hoppers while th ey are still the egg from the cle ments. The size and shape of Ul ncenrrared on til eir "egg beds" and befo re the), th e pods vary with th e spec ies and may be from V2 sprea d to ad joining crops. This ca ll s for ea rl y action t() I II.! in ches long and ~ in ch or le ss wide. They soon after the), hatch. This advice appli es to th ose look like small pell ets of hardened mud (fig. 4). loca li ties where th e egg- lay in g grounds arc we ll de Description and Location of the Eggs lin ed and li m ired in size. Wh(;ll entomologisrs make egg surveys to predi ct infest,tri on rh e foll owing year, Eggs of the differential and two-s triped g rass these arc th e places rh ey exa min e, beca use egg pods Ih)ppers :Ire o li ve co lor and about I I ,. in ch in leng"l. are easy to find. Those of the migratory and red-legged g ra ss hoppers In Missouri, however, the term "grass hopper egg bed" ha s lirt ie mea ning either in control pro gram s or for making egg surveys, be ause th e egg bed usuall y in cludes all th e pas tureland as we ll as field margin s, alfalfa field s, and grain stubble: on a farm. It may also in clud e th e margin al portions of wood lots and so me waste areas. To tell a farmer to spray hi s gra ss hopper egg beds ea rl y is to tell him to spray from half ro most of hi s farm . It is im pos sib le ro mak e an accurate grass ho pper survey in Mi ssouri beca use of th e type and ex tent of breeding places. Hatching Fig. 4-Eggs of the differential or big yellow grass In the spring when th e so il temperature has reac h hopper in clump of sod. ed 60 ° F for :l number of da ys, the hoppers begin -9- hatching. The cap in {"he top of the egg pod serves as an escape for the young grasshoppers. They break through the outer egg shell and worm their way to the top of the ground while covered completely by a skin. The young hoppers appear to be sprouting as they come up out of the soil. At the surface, the sheath splits and the grasshopper frees hi mself. You see the remains of these first cast skins as small white pellets on the ground. Often the hoppers do not have the use of the egg cap as an escape hatch, because during the winter soil covers the pods and the hoppers have to work their way out through it. In normally packed dirt, if this distance is much greater than 1;-2 inches, they die in their tunnels. At depths of four inches or in hard-baked ground, hatching grasshop pers fail to reach the surface. A light rain can free them from hard ground, and you may notice greatly increased hatching after a rain. Deep fall or spring plowing, which buries the eggs four inches or more, can prevent hatching, if the soil is not lumpy but loose enough to pack and form a firm cover over the buried eggs. Many eggs of the migratory and two-striped grasshoppers go into the winter with the embryos partly developed. When soil temperatures rise above 60° F in the spring development resumes. Eggs of the differential grasshopper show no development at the beginning of winter. This is probably ·the rea son why this species and the red-legged grasshopper Fig. 5-Five nymph stages and adult in the develop hatch about three weeks later than the migratory ment of the grasshopper. About three times natural and two-striped grasshoppers. size. The young hopper will not develop in the egg at temperatures below 60° F. Above this point and The spring and early-summer hatching period within a· normal range, the rate of development is for any of these four species lasts four to six weeks. related to temperature. The higher the temperature Altogether, hatching may extend over 10 to 12 the sooner the hatch. A warm, dry spring brings on weeks. For the second-generation migratory species, an early hatch, while a cold, wet spring causes a late this period is a month to six weeks in July and hatch. August. In Missduri, as observant farmers have re The effect of temperature on egg development ported, there are grasshoppers hatching all summer. is cumulative. Each period of temperatures above 60° F helps growth until hatching takes place. This How a Young Grasshopper Develops is an adaptation to the changing temperatures of A newly hatched grasshopper looks like a spring. If grasshopper eggs were like chicken eggs, miniature of its parents, less than lA-inch long: It is this heating and cooling would kill theembryo. covered with a hard shell stronger than bone. Be- -10- cause this tough shell is not elastic, the grasshopper pairs of them. When the grasshopper is not in flight, casts its skin five to seven times in growing up. the forward pair of narrow wings lie alongside and Each time the skin is cast, we see changes other than over the body, covering the hind pair, which are increased size. (Figure 5) . During the last two stages, broad, fanlike, and folded up underneath. In flight, the immature wings are padlike structures pointed both pairs unfold and spread out to the side. upward at the shoulders, where before they are point About two weeks after reaching the adult stage, ed downward and less noticeable. the males and females start mating. In another week Temperature plays an important part in the rate the females commence laying eggs. Mating occurs that young grasshoppers develop. Below 70 0 and between the times eggs are deposited. This ends only above 95 0 F. they show very little growth ot activity. with death. Within this range the higher the temperature, the The old grasshoppers disappear gradually in the faster they grow and more active they are. fall, slowly dying off a few at a time. Even after we Generally, from hatching to adulthood takes think that the cold weather may have killed them three months, between April 10 and July 10. For the all, we may find a few old ragged females still laying second-generation migratory grasshopper this period eggs during a warm spell in late October or early is July 1 to September 20. November. There is a group of overwintering grasshoppers Adult Stage that reverses this whole process. They hatch in the After the last molting of the skin, the fully de late summer and early fall and go through the win veloped wings emerge from the pads. The grass ter as nymphs. You may see them moving around hopper has come of age and reached full size. Adult on a warm day in the middle of winter. Even in our migratory grasshoppers may appear as early as May northern plains states they have often been seen hop 15, while the grown differential grasshopper may not ping about among patches of snow on a warm sunny show up until after July l. hillside. Hardly a winter passes that some one, see There are some short-winged, sometimes incor ing them, does not report an early hatch of grass rectly called wingless, grasshoppers, but in Missouri hoppers taking place. These hoppers reach the adult all the important species are long-winged. Having stage early in April and May. They are not of eco wings is a mark of adulthood, and there are two nomic importance. HOW GRASSHOPPERS LIVE Feeding A grasshopper has a pair of strong, broad jaws, chewed in them. Even the rubber tread on the run which work sideways, in and out, like a pair of scis ning boards of early model automobiles was roughed sors. The hopper is chiefly occupied with only one up by the pests. A person standing in a field was thing-its appetite. It prefers green succulent plant soon attacked by them. They would climb up on food, but can subsist on dry organic matter. During him and bite hard enough to draw blood. They some past severe outbreaks of the differential grass stripped trees of their leaves, and in many places, hopper, all the green plant food was practically gone the limbs of bark. At such times they displayed a by July. Then the grasshoppers entered houses and restless savagery in their actions. chewed holes in the curtains and upholstery. Clothes Grasshoppers prefer small grains to corn or al in a washing hung outdoors to dry soon had holes falfa, but alfalfa is especially susceptible right after -11- the first or second cutting, when grasshoppers will known to disperse on foot up to ten miles from their feed on the new shoots. This feeding checks the hatching place. More often this dispersal is less than growth and if continued will eventually kill the five miles. Some may never leave the pasture where plants. Corn will be eaten into the ground at any they hatched. Missouri grasshoppers for the most time when there are enough grasshoppers. Damage part do not wander far on foot. to corn when there are fewer grasshoppers usually Nymphal migrations have been closely watched. comes later, when it is silking and tasseling. They One of these was from a destroyed alfalfa field across will eat down into the cob, blasting 25 to 60 per a field of corn half a foot high, and into a green cent of the kernels even when the leaves show little barley field across a road. As they passed through damage. They sometimes chew leaves to the mid the corn, the young hoppers would deviate two to rib or cut them off at the axil. The riddled leafless four feet from the line of march to clamber up on cornfield is a common sight during bad grasshopper the young plants. There they would take a few nib years. bles, climb down, and pass on again with the mi Grasshoppers seem to have some aversion to grating horde. Apparently they knew where they most varieties of sorgo, except for the heads when were going and why. they first appear. They will attack sorgo leaves as a More than 2500 years ago, the prophet Joel last resort. Cutting off of the heads of wheat and wrote about a locust plague symbolic of the mystic barley and the bolls of flax, the shattering of oats, forces of destruction. Of migrations he said: and the chewing of the leaves, blossoms, and seed "They shall run like mighty men; they pods of alfalfa are typical forms of grasshopper dam shall climb the wall like men of war; and age. They will also eat weeds, such as sunflowers, they shall march everyone on his ways, and ragweed, and wild lettuce, especially when the plants they shall not break their ranks. Neither shall one thrust another; they shall walk everyone are young and tender. in his path; and when they fall upon the As a grasshopper grows it naturally eats more. sword, they shall not be wounded." He also In the last two stages of nymphal development and went on to say: "They shall climb up upon the first two weeks of adulthood it reaches its peak the houses; they shall enter in at the windows of destructiveness. In a season this may mean a like a thief" (Joel II:7-9) . month to six weeks. After this, the feeding becomes Many a housewife on the farm has experienced more desultory, as the grasshoppers become occupied the same thing much to her disgust and anguish. All with reproduction. through history man has had to share some parr, large or small, of his food and comfort with the Migrations grasshoppers, and their ways are eternal. One of the chief characteristics of the economic Adult migrations are accomplished on the wing. species of grasshoppers is their urge to be on the Usually these flights are local, from a destroyed field move. We notice this migratory habit when they upwind toward a standing crop which offers more reach the third and fourth nymphal stages, particu succulent food. The movement consists of low flying larly under crowded conditions. In late June and jumps until the crop is reached. A typical swarming July the differential grasshopper is often seen cross flight begins with a restless milling in a field, which ing the road on foot. Where hatching takes place increases with the temperature until the air is full of along the margin of a crop, the newly hatched hop circling grasshoppers. If there is any wind, the whole pers soon start sifting into the crop, but this is not swarm takes off in the direction the wind is blow a typical migration. The migratory movement is one ing. A strong wind will carry them several miles. of concerted action in one direction by the entire Such flights usually commence about 11 :00 a.m. and population. In some parts of the country where end about 4:00 p.m. on sunshiny days. By shading crops are scattered, young grasshoppers have been your eyes against the edge of the sun you can recog- -12- nize flashes of silvery reflected light coming from the linked with drouth conditions, and rightly so. Dur wings of flying grasshoppers. ing wet" years grasshoppers are not nearly the prob lem they are during dry years. On the other hand, Weather Affects Grasshoppers weather is not the sudden destroyer we might think. The weather plays an important part in what a Whenever there is a spell of unusually hot, cold, or grasshopper does and whether it will live to do it. wet weather, the common notion arises that "this Its body temperature goes up and down with the should kill off all the grasshoppers." According to surrounding air temperature. It cannot protect itself scientists, grasshoppers have been around for some from temperature changes like a human. All its ac 200 million years. They have had to put up with tivity is geared to the existing temperature. weather conditions such as we have never seen and Between 70° and 90° F. activity increases with they have survived. the temperature. Above or below these points the grasshopper slows down. It is likely to move to seek more favorable temperatures. In cold weather hop CONTROL OF GRASSHOPPERS pers will hide in weeds and under trash seeking warmth. In hot weather they will roost as high off Natural Control the ground as possible; if adult they will take to the alr. When grasshoppers appear in great numbers, When grasshoppers hatch, they must have food one of the questions asked is "Where did they all within a short time or die. If the temperature is be come from?" The answer is that, for species having low 70° F. for three or more days, the hoppers would one generation annually, they came from the grass be inactive, not eat, and die. Continued cold weather hoppers that were present the year before, unless they following a general hatch has frequently killed off have just arrived by air. A grasshopper population whole infestations. If the young hopper can survive is made up of half males and half females. Each fe the first week or ten days of development, he stands male will lay 200 to 300 eggs. The following year, a chance of reaching maturity. if all these eggs hatched and the hoppers all survived, Since grasshoppers do most of their feeding be we would have 100 to 150 times as many grasshop tween 70° and 90° F., an insecticide used on plants pers. This never happens, or we would be buried by the grasshopper eats should be applied when the the pests in one year's time. temperature is in this range. Fortunately nature maintains a balance by cut Heavy rains or even hailstorms do not often ting down on the enormous numbers of young. drown or beat the life out of grasshoppers. Usually With grasshoppers the natural balances are weather, when the weather clears off they emerge from their parasites, predators, and disease, which annually hiding places. Egg pods in the sod buried under take care of at least 90 percent of this "100 to 150 water for months have hatched at the water line as times" potential. the water receded. However, eggs may rot under There are two common beetles and one fly wet conditions. Extremely hot, dry weather in late whose larvae feed on grasshopper eggs in the pod. August and September has been known to cook eggs These are blister beetles, ground beetles, and bee fly that were loosely laid in exposed clumps of short larvae. In some places they may destroy from 25 to grass. 75 percent of all the eggs in one season. There is There is usually enough moisture in the soil in also a mite that sucks the juice from the eggs. Vari the spring to permit eggs to hatch. However, the ou~ birds, ground squirrels, field mice, and skunks ground has sometimes been too dry and hard. Then will feed on the eggs, especially where the pods are hatching was delayed until late rains came to wet congregated in great numbers and easily reached. and loosen the soil. There is a wasp that parasitizes the eggs soon after Over the years, grasshopper outbreaks have been they are laid. It works its way down into the pod -13- and lays its eggs in the grasshopper's eggs, and in alfalfa, and other crops insures an abundant late food the spring a wasp emerges instead of a grasshopper. supply after the small grains and hay are cut. Flesh flies and others deposit eggs or living lar Since grasshoppers will not breed in well-tilled vae on the grasshopper. Eventually the larvae of fields, the pastures, margins, and fields of alfalfa and these flies enter the body of the grasshopper and eat clover are the chief sources of infestation. Where it up from the inside. stubble fields are thoroughly worked either in the In Missouri whitish balls of tightly coiled fall or early in the spring before the eggs hatch, threadlike worms are often dug up out of the soil. the infestations in these fields are usually destroyed. These are the round worms ( Nematodes) which para In the wheat states where clean summer fallow is sitize grasshoppers. Inside the grasshopper these practiced, proper tillage becomes an important con worms sometimes reach the great length of 17 inches trol measure. and are tightly coiled, filling the whole of the body Control with Insecticides cavity. There may be up to 40 worms in one grass hopper, but one is sufficient ro kill it. Up to 30 per For 75 years poisoned bran or bran-sawdust cent of grasshoppers may be parasitized by these mash was used to control grasshoppers. At first arse worms. nic in various forms and then sodium fluosilicate Fungus and bacterial diseases destroy grasshop were the poisons used in the mash. The mixture pers when conditions are right. Grasshoppers attacked was broadcast by hand or machine at the rate of 20 by a fungus disease will assume a characteristic posi pounds per acre. The effectiveness of the bait de tion on the stem of a plant, clasping it with the pended upon how many of the grasshoppers ate it. front and middle legs. The head is always up, and In order to draw them to the bait, scientists tried a the grasshopper dies and remains in this clinging n umber of attractants. They tested banana oil, citrus position. Local grasshopper infestations are often fruits, molasses, melons, and about 30 other sub wiped out by fungus diseases which show up during stances in the mash. After thousands of tests they warm muggy weather. realized that the wet bran or bran-sawdust as a car Weather as a factor in destroying grasshoppers rier of the poison was all they needed. They got has already been discussed in its effect on hatching best results in dry weather when there was not much and the development of the young. Some newly green vegetation. However, poisoned bait was far hatched nymphs no doubt are destroyed each year from being a sure method of control. by inclement weather. In the 1940's the chlorinated hydrocarbon com These are the more common natural enemies pounds appeared. They soon proved to be excellent of the grasshopper. There are others. One wonders grasshopper killers when used in sprays. Toxaphene how we could have any grasshoppers left, but as and chlordane were the first of these compounds. with many other animals, nature has made grass They were soon followed by aldrin, dieldrin, and hoppers prolific in order that they can survive all heptachlor. Very small amounts, such as one or two these hazards. pounds of the first two, and one or two ounces of the last three insecticides per acre, often gave 100 Effect of Tillage percent kills. Breaking up the original sod of our native To be effective against grasshoppers, an insecti prairies and seeding it with crops has had a tremen cide must have a lasting effect, to kill off any late dous influence on the life and numbers of our grass comers from hatching or migration. The chlorinated hoppers. In Missouri it has produced conditions for hydrocarbon sprays do this. They are effective one to cyclic outbreaks of the so-called native species. three weeks, depending upon the compound and Grazing pastureland makes a short-grass sod dosage used. condition favorable for those grasshoppers which The long residual effect of these compounds choose grass clumps for egg laying. Growing corn, poses a serious problem in pasturing or feeding live- -14- II { Differential ~§~§]§§§~§§§~~I::'~:': ' :~':':'~:':':~':':'~:':'~: ':':~.:.:.~:.:.:~.:.: .;':.:.:'!7:.:.:.:':'::.:.:'!7:.:.:.':':'::.:.::':".:.:.':':':.:.:':":.:.:':':'.:.:. ~:.:.:':':'.:.: .~:.: .:~.:.; .~:.:.:~.:.:.~:.:.:~.:.:.~:.: . ::::::.:.:.:::::::. :.:d.:. : Red legged {~~~~~~I~~~f::::~':':::~':':' :~'; ' :':':::':':':':':' :.:.:.:.:.:.:.:.:.:.:.:.:.:.:. :.:.:.:.:.: .: . :. :.:.:. :.:.:.:.:.:.:.:-:.:.:.:.:.:.:.:.:.:.: . :.: .:.:.:. : .:.: . :.:.:.: Spray dosages ~:: ; : : ::"": : :" " """'J 900 1------.-~ t-f-.--::".=-r- FI="'f- I:-f- f- ~ --.--'= - - - - } MostEffechve . 5-day mean max. temp,:..- _ r-_ - _ - _ Temperature 0 80 - r- r- .-- - r- - Range for r-f-- I-- I- Spraying 7~~~~--~f-f--~~f-~f--f-~---f-f--f-~f--f-~------~--- 60°f- t-- n 500 10 20 30 10 20 30 9 19 29 9 19 29 8 18 28 7 17 27 7 April May June July August September LEGEND I Stages of Development [ I [;{:;:;:;:;:;:;:;:;:;:;:;:;:;:;:;:;:;:;:;:;:1 (Hatching) (Nymphs) (Adults) Spray Dosages ~ j:: : :: : : : : : : :: : : : : : :1 (Light) (Medium) (Heavy) Fig. 6-Spray schedule in relation to seasonal history and temperature, Ash Grove, Missouri, 1956. stock. Residues may appear in the fat or meat and Spraying for Grasshoppers in Missouri show up in the milk of animals that have fed on In 1955 a cooperative state and federal research treated forage. There are restrictions on pasturing project was conducted to find a grasshopper control and feeding livestock to avoid harmful residues from method fitted to Missouri conditions. Research work such sprays. These are printed on insecticide labels ers made large-scale spray tests with aldrin, dieldrin, and in the recommendations for grasshopper control and heptachlor applied at recommended dosages. put out by the University of Missouri Extension They selected a block of farms totaling 2,987 acres Service. in the southwest part of the state for the tests. They You should consider weather conditions in us sprayed 1,388 acres in 1955 and 2,192 acres in 1956. ing any insecticide. Apply the sprays when the grass Their main objective was to see how much spraying hoppers are active. Below 70° F. the grasshoppers it would take to control all the grasshoppers in one are not feeding and spraying at this time is not im season. They checked to see what effect this spraying mediately effective. If spray is applied under this had on infestations the following years. Several farms condition, its residual action will still destroy grass outside the treated area were included in the check. hoppers providing above 70° temperatures return The sprays were applied with a turbine-blower spray within two or three days. Above. 90°, or when grass er with a side-delivery nozzle at 1 to 21;2 gallons per hopper are full grown, you should double the dosage acre in a 2- to 3-rod swath. They kept records of the for best results. development and activities of grasshoppers, weather, and anything else that might influence results. bers can be expected from the use of aldrin or hep Conclusions from Spray Tests tachlor at 2 ounces, or dieldrin at 1 ounce, per acre before daily temperatures of 90° F. occur and before Several conclusions were reached from these the grasshoppers reach the last stage of development. tests: This usually means before June 15. Thereafter dos 1. The main sources of grasshopper infestation ages must be increased to twice these amounts. (Fig. in southwestern Missouri are the pasturelands, in 6 ). cluding marginal wood lots, alfalfa, and field mar 4. Grasshopper migrations on foot become gins. Control on the satching grounds may require noticeable in late June. In years of severe infesta spraying all the pastureland and alfalfa on a farm as tions, flights take place after the middle of July. Mi well as the field margins. This may include from half grating grasshoppers are probably the major source to three-fourths of a farm. It is sometimes difficult of reinfestation of treated fields. In July and August to cover all the sources of infestation, since areas a second and sometimes a third treatment of a field such as wood lots or waste places are too rocky, is necessary to protect crops. Spraying at this time woody, or bushy to allow access with spray equip causes little damage to crops. It was demonstrated ment. that 95 to 100 percent of the grasshoppers in com 2. The hatching period of the most important six to eight feet high can be destroyed by spraying species in Missouri begins about April 10 and may with ground equipment at this time. About 5 per last for 10 to 12 weeks. Beginning in mid-July there cent of the corn plants were knocked down by the is another hatching period, for the second-generation spray truck. migratory grasshopper, which lasts for five or six 5. Residue toleran'ces and intervals between the weeks. Spraying should be timed so that one appli application of the insecticide and the feeding or pas cation will get as many of the young hoppers as turing of livestock have been established for some possible. This usually means waiting until June 1. insecticides. Ask your county agent for the latest By the time the hatching of the differential grass restrictions on the use of grasshopper insecticides. hopper is far enough along for treatment, some 6. Using insecticides on crops and pastures may adults of the migratory grasshopper will be ready to or may not affect grasshopper populations in those lay eggs for its second generation. When these two fields the next year. Reinfestations do occur in treated species are in a mixed infestation, it is practically fields, mostly from second-generation grasshoppers impossible to get all the hoppers in one spraying. or those moving in from untreated places. These A careful check on the infestation in any field will reinfestations limit the effectiveness of control to determine when it should be treated. one year. 3. From 95 to 100 percent reduction in num- . ,', I~ .Mjsso.uri, gra$sh~ppe~~ in dam~ging nulllbers caQ. be e~p~cted.l>.eri : ' '. :, Qdica1{y ¥O,tlg,wit.h dry years. ,They can be controlled with orgamc 11lSectJ.C1dal , :" Spl'~rS to 'pr()t~c.;taU ,crops and pastures from damage. . ".' .' . "," The mai~ sol.li-ces,o t;.gtassJ;lOpper infestatioQ.are past\lresa;nd haylan4, !u- " ~ludi.p.g : Watg~l ~odql¥.ld,alfa~(a and dover fieldsa.n,d 6e~4 m~rgj~s. ~ev~nI:. I .": fipto:rss\lch ;lslWgra.~ons a~d {he inability, to treataU . so~~ces of/nfesta~lQ~ ." liinit'-' the , ~ffeCtiv.enes~~' ofcQntrol toone yeii. No t: ; ijl : gra~s.hopper 1nfest~t18~, . ·· · ·:~~:~r~~~~.~~~=. · ~;::;~t~;~;~~~~.j;~:i~ / ..· : ·':i;'~ ~~ ,s;Pr.ay~~g,,~1~W?4!9 . ~e., S~ ,',:. ..~.. '. ' . , . "···'g.l~]1;~",:,