Aeropedellus clavatusClubhorned Grasshopper

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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)

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)

  • 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)

  • 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)

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)

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)

  • 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)

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)

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)

  • 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

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)

Commensal/Parasitic Species
  • nematode, Spirura infindibuliformis
  • protozoan, Nosema locustae

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.

Contributors

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

Glossary

Nearctic

living in the Nearctic biogeographic province, the northern part of the New World. This includes Greenland, the Canadian Arctic islands, and all of the North American as far south as the highlands of central Mexico.

World Map

acoustic

uses sound to communicate

agricultural

living in landscapes dominated by human agriculture.

asexual

reproduction that is not sexual; that is, reproduction that does not include recombining the genotypes of two parents

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.

chemical

uses smells or other chemicals to communicate

cryptic

having markings, coloration, shapes, or other features that cause an animal to be camouflaged in its natural environment; being difficult to see or otherwise detect.

diapause

a period of time when growth or development is suspended in insects and other invertebrates, it can usually only be ended the appropriate environmental stimulus.

diurnal
  1. active during the day, 2. lasting for one day.
ectothermic

animals which must use heat acquired from the environment and behavioral adaptations to regulate body temperature

fertilization

union of egg and spermatozoan

folivore

an animal that mainly eats leaves.

herbivore

An animal that eats mainly plants or parts of plants.

heterothermic

having a body temperature that fluctuates with that of the immediate environment; having no mechanism or a poorly developed mechanism for regulating internal body temperature.

internal fertilization

fertilization takes place within the female's body

metamorphosis

A large change in the shape or structure of an animal that happens as the animal grows. In insects, "incomplete metamorphosis" is when young animals are similar to adults and change gradually into the adult form, and "complete metamorphosis" is when there is a profound change between larval and adult forms. Butterflies have complete metamorphosis, grasshoppers have incomplete metamorphosis.

motile

having the capacity to move from one place to another.

mountains

This terrestrial biome includes summits of high mountains, either without vegetation or covered by low, tundra-like vegetation.

native range

the area in which the animal is naturally found, the region in which it is endemic.

oviparous

reproduction in which eggs are released by the female; development of offspring occurs outside the mother's body.

polygynandrous

the kind of polygamy in which a female pairs with several males, each of which also pairs with several different females.

seasonal breeding

breeding is confined to a particular season

sedentary

remains in the same area

solitary

lives alone

tactile

uses touch to communicate

temperate

that region of the Earth between 23.5 degrees North and 60 degrees North (between the Tropic of Cancer and the Arctic Circle) and between 23.5 degrees South and 60 degrees South (between the Tropic of Capricorn and the Antarctic Circle).

terrestrial

Living on the ground.

tropical savanna and grassland

A terrestrial biome. Savannas are grasslands with scattered individual trees that do not form a closed canopy. Extensive savannas are found in parts of subtropical and tropical Africa and South America, and in Australia.

savanna

A grassland with scattered trees or scattered clumps of trees, a type of community intermediate between grassland and forest. See also Tropical savanna and grassland biome.

temperate grassland

A terrestrial biome found in temperate latitudes (>23.5° N or S latitude). Vegetation is made up mostly of grasses, the height and species diversity of which depend largely on the amount of moisture available. Fire and grazing are important in the long-term maintenance of grasslands.

tundra

A terrestrial biome with low, shrubby or mat-like vegetation found at extremely high latitudes or elevations, near the limit of plant growth. Soils usually subject to permafrost. Plant diversity is typically low and the growing season is short.

visual

uses sight to communicate

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.