Animal Diversity Web

Ge­o­graphic Range

Aero­pe­del­lus clava­tus, the club­horned grasshop­per, is na­tive to the Nearc­tic re­gion, and is found through­out west­ern Canada and the United States. Its range ex­tends north­ward into Alaska, and in Canada from the west coast to Man­i­toba. In the United States, it is com­mon through­out the mid-west­ern states, north from Mon­tana and the Dako­tas, east to Wis­con­sin and Iowa, and south through Utah, Col­orado, New Mex­ico, and Ari­zona. (Ham­rick and Ham­rick, 1989; Otte, 1981)

• Biogeographic Regions
• nearctic
  • native

Habi­tat

Aero­pe­del­lus clava­tus is typ­i­cally found ei­ther in low prairie habi­tats from about 1740 to 2600 m, or in alpine habi­tats from the tim­ber­line (3350 m) to 4150 m. In Canada and the north­west­ern United States, they live in low el­e­va­tion prairies, grassy fields, and pas­tures. Far­ther south in the United States, these grasshop­pers are found in moun­tain mead­ows and tun­dra habi­tats. In­ter­est­ingly, pop­u­la­tions of club­horned grasshop­pers are not found in el­e­va­tions be­tween those two ex­tremes. Both prairie and alpine habi­tats usu­ally have much grass or sedge veg­e­ta­tion, as those are these grasshop­pers' main food sources. (Alexan­der and Hilliard Jr., 1964; Coxwell and Bock, 1995; Hadley and Mas­sion, 1985; Ham­rick and Ham­rick, 1989; Otte, 1981; Pfadt, 2002)

• Habitat Regions
• temperate
• terrestrial

• Terrestrial Biomes
• tundra
• savanna or grassland
• mountains

• Other Habitat Features
• agricultural

• Range elevation

  1740 to 4150 m

  5708.66 to 13615.49 ft

Phys­i­cal De­scrip­tion

Aero­pe­del­lus clava­tus is a medium sized grasshop­per species. It ex­hibits sex­ual di­mor­phism, with fe­males being longer than males. Males mea­sure at 16 to 20 mm, while fe­males are 18 to 25 mm in length. These grasshop­pers have a slanted face, and the an­ten­nae have 6 large, dark ter­mi­nal seg­ments that form a club, which give this species it's com­mon name of "club­horned". They are gray or green col­ored with mark­ings on them. The side of the face has a dark streak on it from the bot­tom of the eye to the mandible, with an an­te­rior ver­ti­cal white band. Males have forewings that ex­tend to or be­yond the end of the ab­domen, while fe­males have much shorter forewings. The front tib­iae is also thicker in males.

Nymphs re­sem­ble adults, though lack­ing wings and the an­ten­nal club. They are iden­ti­fi­able by their strongly slanted face, flat an­ten­nae, and the nar­row light line be­hind the eye, which runs along the side of the head onto the body. The last two in­stars have erect wing pads, which the first two in­stars lack. Size in­creases reg­u­larly be­tween molts. Clavate an­ten­nae are pre­sent as early as the sec­ond in­star, but the in­flated tibia of the male does not ap­pear until the last molt. (Otte, 1981; Pfadt, 2002)

• Other Physical Features
• ectothermic
• heterothermic
• bilateral symmetry

• Sexual Dimorphism
• female larger
• sexes shaped differently

• Range length

  16 to 25 mm

  0.63 to 0.98 in

De­vel­op­ment

Aero­pe­del­lus clava­tus is hemimetabolous. Eggs are laid in late sum­mer, and enter di­a­pause for the win­ter. In lower el­e­va­tions, eggs hatch the fol­low­ing spring after one win­ter. In high el­e­va­tion pop­u­la­tions, eggs di­a­pause for 2 or even 3 win­ters be­fore hatch­ing. Eggs hatch very early in the spring; there may still be snow and ice on the ground. Hatch­ing oc­curs ear­lier at lower el­e­va­tions. In plains habi­tats, they hatch in the first week of May, while in moun­tain areas, hatch­ing be­gins in mid to late June. Hatch­ing oc­curs over a pe­riod of 3 to 4 weeks, though in­di­vid­u­als that hatch in July in alpine habi­tats often will not de­velop into adults be­fore win­ter ar­rives. As an adap­ta­tion to bo­real habi­tats, nymphal de­vel­op­ment is very quick, and A. clava­tus has only 4 in­stars (most Acri­di­dae have 5 in­stars). De­vel­op­ment takes about 30 days in plains habi­tats, and about 42 days in alpine habi­tats. The first in­star lasts no more than a week, while the last two in­stars prob­a­bly last for longer pe­ri­ods of time. They are sex­u­ally ma­ture 6 weeks after hatch­ing. The ac­cel­er­ated de­vel­op­ment al­lows for adults to be pre­sent when grasses and sedges are still avail­able dur­ing the short grow­ing sea­son. Males ap­pear to ma­ture ear­lier than fe­males, and by the end of sum­mer into fall, there are more fe­males pre­sent than males. (Alexan­der and Hilliard Jr., 1964; Coxwell and Bock, 1995; Otte, 1981; Pfadt, 2002)

• Development - Life Cycle
• metamorphosis
• diapause

Re­pro­duc­tion

There is lit­tle in­for­ma­tion avail­able on the mat­ing habits of Aero­pe­del­lus clava­tus. They are likely polyg­y­nan­drous. Stridu­la­tion is likely a sig­nif­i­cant part of the courtship rit­ual, where the male vi­brates the hind femur through a small arc against a vein on the tegmen, pro­duc­ing a "song" that fe­males can use to iden­tify pos­si­ble mates of the same species. (Pfadt, 2002)

• Mating System
• polygynandrous (promiscuous)

Fe­males oviposit amongst the roots of grasses or sedges. The eggs are light tan in color, 4.6 to 5.5 mm long, and are laid in pods. Each egg pod has 5 to 8 eggs, with the eggs in two rows. The pod is 10 to 13 mm long and 4 mm in di­am­e­ter, and the pod is made up of a tan, hard­ened froth. The egg pods are ori­ented ver­ti­cally in the soil or amongst clumps of grass. Mul­ti­ple egg pods may be laid to­gether in a sin­gle spot, and the same spot may used re­peat­edly, with new pods being laid on or even in old pods. The eggs enter di­a­pause shortly after, and do not emerge until the fol­low­ing spring for prairie pop­u­la­tions, or after two or three win­ters for alpine pop­u­la­tions. Ovipo­si­tion usu­ally takes place dur­ing the late sum­mer, from Au­gust until Sep­tem­ber in high el­e­va­tion pop­u­la­tions. There is one gen­er­a­tion an­nu­ally in plains habi­tats. Aero­pe­del­lus clava­tus reaches sex­ual ma­tu­rity in 4 to 6 weeks after hatch­ing. (Coxwell and Bock, 1995; Ham­rick and Ham­rick, 1989; Pfadt, 2002)

• Key Reproductive Features
• seasonal breeding
• gonochoric/gonochoristic/dioecious (sexes separate)
• asexual
• fertilization
  • internal
• oviparous

• Breeding interval

  Aeropedellus clavatus can mate many times throughout its life.

• Breeding season

  Mating and oviposition take place in the late summer.

Fe­males pro­vide pro­vi­sion­ing in the eggs, and also lay the eggs in an egg pod made of a hard­ened froth. The egg pods are placed in the soil at the roots of a clump of grass, pro­vid­ing pro­tec­tion. After this, the fe­males leave the eggs and pro­vide no fur­ther parental care. (Pfadt, 2002)

• Parental Investment
• pre-hatching/birth
  • provisioning
    • female
  • protecting
    • female

Lifes­pan/Longevity

The spe­cific lifes­pan for Aero­pe­del­lus clava­tus is un­known, but most grasshop­per species live for a month or two after reach­ing adult­hood. Eggs are laid in late sum­mer or early fall, sur­vive through the win­ter, and hatch in early spring. Hatch­lings take about 6 weeks to ma­ture, and then adults prob­a­bly sur­vive for 1-2 months. So total life span might be 9-14 months. Pre­da­tion can be very high for this species, so lifes­pan is often short. Those that sur­vive through­out adult­hood will die when win­ter ar­rives, typ­i­cally in Sep­tem­ber in alpine habi­tats. How­ever, some eggs, par­tic­u­larly those laid at high al­ti­tude, may not hatch until 2 or 3 win­ters have passed, so this species can, rarely, have a much longer total lifes­pan. (Coxwell and Bock, 1995; Pfadt, 2002)

• Range lifespan
  Status: wild

  3.5 (high) years

• Typical lifespan
  Status: wild

  9 to 14 months

Be­hav­ior

Aero­pe­del­lus clava­tus is ac­tive dur­ing the day. Fe­males are not able to fly, as their wings are too short, but males fre­quently make short flights. In be­tween flights, they crawl on the ground. Fe­males are less ac­tive and slower, and can often by found mo­tion­less on the ground. Since they are ec­tother­mic, they usu­ally have to warm them­selves in the sun, often in the morn­ing. To main­tain their body tem­per­a­ture, they bask in the sun, and are more ac­tive dur­ing times of in­tense sun­light, es­pe­cially in alpine habi­tats. They are also much less ac­tive dur­ing storms and other un­fa­vor­able weather con­di­tions. In the prairies of Canada, they can have very high den­si­ties, with as many as 20 grasshop­pers per square yard. In most other areas, den­sity is lower at 1 to 4 adults per square yard. Males of this species may be ter­ri­to­r­ial, but there is not enough in­for­ma­tion on this. (Coxwell and Bock, 1995; Ham­rick and Ham­rick, 1989; Pfadt, 2002)

• Key Behaviors
• flies
• diurnal
• motile
• sedentary
• solitary

Home Range

Aero­pe­del­lus clava­tus typ­i­cally stays in the same gen­eral area of where it hatched. (Pfadt, 2002)

Com­mu­ni­ca­tion and Per­cep­tion

Aero­pe­del­lus clava­tus has com­pound eyes, al­low­ing it to see its en­vi­ron­ment, as well as de­tect preda­tors. It uses its an­ten­nae to iden­tify food plants, by tap­ping its an­ten­nae, as well as its palps, on leaf sur­faces. Sen­silla on these parts de­tect chem­i­cals and allow the grasshop­per to find plants to eat. Phys­i­cal touch elic­its es­cape be­hav­iors. As is char­ac­ter­is­tic of many Or­thoptera, stridu­la­tion is used to com­mu­ni­cate be­tween in­di­vid­u­als. Males make a "song" by vi­brat­ing their back femur against the tegmina. Each species has its own unique sound, al­low­ing in­di­vid­u­als to iden­tify their own species. Stridu­la­tion is likely used in the courtship process to com­mu­ni­cate with pos­si­ble fe­male mates. (Pfadt, 2002)

Club­horned grasshop­pers have eyes that let them see the en­vi­ron­ment around them, and also de­tect preda­tors. They use their an­ten­nae and mouth parts to find food. By tap­ping their an­ten­nae and mouth parts on leaves, they can de­tect chem­i­cals from the plant to de­ter­mine if it is a plant they can eat. Phys­i­cally touch­ing the grasshop­pers usu­ally causes them to hop away to es­cape. To com­mu­ni­cate with each other, males make a "song" by vi­brat­ing their back leg against their wing. Each species makes a dif­fer­ent sound, which lets in­di­vid­u­als find oth­ers of their own species, and also lets mates find each other. (Pfadt, 2002)

• Communication Channels
• acoustic

• Perception Channels
• visual
• tactile
• chemical

Food Habits

Club­horned grasshop­pers are her­bi­vores, and feed mainly on grasses and sedges. Alpine pop­u­la­tions also feed more on forbs than lower el­e­va­tion pop­u­la­tions. They have been recorded feed­ing upon 28 species of grass, and 6 species of sedge. Ex­am­i­na­tions of their crops have also found fungi, pollen, and arthro­pod parts. (Alexan­der and Hilliard Jr., 1964; Otte, 1981; Pfadt, 2002)

• Primary Diet
• herbivore
  • folivore

• Animal Foods
• insects

• Plant Foods
• leaves
• pollen
• flowers

• Other Foods
• fungus

Pre­da­tion

Gen­eral preda­tors of Aero­pe­del­lus clava­tus in­clude birds, ro­dents, spi­ders, and preda­ceous in­sects such as ants. Prairie birds are sig­nif­i­cant preda­tors, such as the Horned Lark, West­ern Mead­owlark, Chest­nut-col­lard longspur, Sprague's Pipit, and White-Tailed Ptarmi­gan. Their gray and green col­oration can serve as cam­ou­flage, though less in alpine habi­tats where veg­e­ta­tion and the op­por­tu­nity for con­ceal­ment is scarce. To es­cape from preda­tors, these grasshop­pers hop. Males also "prance", which is small, re­peated hops with­out pro­gres­sion. Fe­males are less ac­tive, and are less vig­or­ous than males when es­cap­ing preda­tors. (Coxwell and Bock, 1995; Kevan, et al., 1983; Maher, 1979; Pfadt, 2002)

• Anti-predator Adaptations
• cryptic

• Known Predators

  • birds, Aves
  • Horned Lark, Eremophila alpestris
  • Western Meadowlark, Sturnella neglecta
  • Chestnut-collard longspur, Calcarius ornatus
  • Sprague's Pipit, Anthus spragueii
  • White-Tailed Ptarmigan, Lagopus leucura
  • rodents, Rodentia
  • spiders, Araneae
  • insects, Insecta
  • ants, Formicidae

Ecosys­tem Roles

Aero­pe­del­lus clava­tus serves as prey to birds, ro­dents, spi­ders, and other in­sects. It can be a sig­nif­i­cant her­bi­vore, and can cause dam­age to sev­eral grass and sedge species when found in high den­si­ties. Aero­pe­del­lus clava­tus can be an in­ter­me­di­ate host of the ne­ma­tode Spirura in­find­ibu­li­formis, which in­fects ground squir­rels. It can also be in­fected by the mi­crosporid­ium pro­to­zoan, Nosema lo­cus­tae, which can cause death, though usu­ally only a very small per­cent­age of the pop­u­la­tion is in­fected. (An­der­son, et al., 1993; Ewen and Muk­erji, 1979; Pfadt, 2002)

Eco­nomic Im­por­tance for Hu­mans: Pos­i­tive

There are no known pos­i­tive ef­fects of Aero­pe­del­lus clava­tus on hu­mans.

Eco­nomic Im­por­tance for Hu­mans: Neg­a­tive

Aero­pe­del­lus clava­tus has the po­ten­tial to be a crop pest. It is a pest of grasses and sedges in prairies, moun­tain mead­ows, parks, and pas­tures. In some areas of Canada, these grasshop­pers can have very high den­sity and cause dam­age to grasses, and have also dam­aged seedling ce­re­als in the past. There was a par­tic­u­larly se­vere out­break in Canada in 1936 that de­stroyed 300 acres of wheat. They also in­fest range­land in Mon­tana and North Dakota. There have been at­tempts to con­trol grasshop­per pop­u­la­tions on range­lands by ap­ply­ing the pro­to­zoan Nosema lo­cus­tae, but in­fec­tion rates in Aero­pe­del­lus clava­tus and other Acri­di­dae are too low to be con­sid­ered suc­cess­ful con­trol. (Ewen and Muk­erji, 1979; Pfadt, 2002)

• Negative Impacts
• crop pest

Con­ser­va­tion Sta­tus

Aero­pe­del­lus clava­tus has no spe­cial con­ser­va­tion sta­tus.

• IUCN Red List

  Not Evaluated

• US Federal List

  No special status

• CITES

  No special status

• State of Michigan List

  No special status

Con­trib­u­tors

An­gela Miner (au­thor), An­i­mal Di­ver­sity Web Staff, George Ham­mond (ed­i­tor), An­i­mal Di­ver­sity Web Staff.

Ref­er­ences

Alexan­der, G., J. Hilliard Jr.. 1964. Life His­tory of Aero­pe­del­lus clava­tus (Or­thoptera: Acri­di­dae) in the Alpin Tun­dra of Col­orado. An­nals of the En­to­mo­log­i­cal So­ci­ety of Amer­ica, 57/3: 310-317.

An­der­son, R., E. Barnes, C. Bartlett. 1993. Restudy of Spirura in­fundibu­li­formis Mcleod, 1933 (Ne­ma­toda, Spiruroidea) from Sper­mophilus richard­sonii, with ob­ser­va­tions on its de­vel­op­ment in in­sects. Cana­dian Jour­nal of Zo­ol­ogy, 71/9: 1869-1873.

Coxwell, C., C. Bock. 1995. Spa­tial vari­a­tion in di­ur­nal sur­face tem­per­a­tures and the dis­tri­b­u­tion and abun­dance of an alpine grasshop­per. Oe­colo­gia, 104/4: 433-439.

Ewen, A., M. Muk­erji. 1979. Sus­cep­ti­bil­ity of five species of Saskatchewan grasshop­pers to field ap­pli­ca­tions of Nosema lo­cus­tae (Mi­crosporida). The Cana­dian En­to­mol­o­gist, 111/8: 973-974.

Hadley, N., D. Mas­sion. 1985. Oxy­gen-con­sump­tion, wa­ter-loss and cu­tic­u­lar lipids of high and low el­e­va­tion pop­u­la­tions of the grasshop­per Aero­pe­del­lus clava­tus (Or­thoptera, Acri­di­dae). Com­par­a­tive Bio­chem­istry and Phys­i­ol­ogy Part A- Phys­i­ol­ogy, 80/3: 307-311.

Ham­rick, K., J. Ham­rick. 1989. Ge­netic-vari­a­tion within and among pop­u­la­tions of an alpine grasshop­per, Aero­pe­del­lus clava­tus. Jour­nal of Hered­ity, 80/3: 186-192.

Kevan, P., J. Cant, D. Kevan. 1983. Preda­tor avoid­ance pos­tur­ing of grasshop­pers (Or­thoptera: Acri­di­dae) from the Col­orado alpine and plains. The Cana­dian En­to­mol­o­gist, 115/2: 115-122.

Maher, W. 1979. Nestling diets of prairie passer­ine birds at Mata­dor, Saskatchewan, Canada. IBIS, 121/4: 437-452.

Otte, D. 1981. The North Amer­i­can Grasshop­pers Vol. I. Cam­bridge, Mass­a­chus­setts: Har­vard Uni­ver­sity Press.

Pfadt, R. 2002. Field Guide to Com­mon West­ern Grasshop­pers. Laramie, Wyoming: Uni­ver­sity of Wyoming.