- Apply to UW
- Programs & Majors
- Cost & Financial Aid
- Current Students
- UW Life
- About UW
Apply to UW
Although locally distributed, the mottled sand grasshopper has a wide geographic range in North America. Its preferred habitat consists of sandy soil covered by sparse grasses and forbs. In the West it inhabits the sand prairie where the characteristic vegetation consists of the tall grasses, sand bluestem, and prairie sandreed, as well as several short and mid grasses and numerous species of forbs. Although the mottled sand grasshopper is prevalent in grassy areas with sandy soils, it is a rare species in grasslands with loam to clay soils such as in the mixedgrass prairie. Here, the closely related species, Spharagemon equale, is common. Yet, ruderal sandy loam sites (e.g., edges of wheat fields, roadsides, and other disturbed areas) provide favorable habitats for the mottled sand grasshopper where it may build up to unusually high densities.
In an eastern Wyoming sand prairie, observations were made of adults feeding on grass and ground litter. A summary of these observations attests to the geophilous behavior of this species. Crawling on the ground, a hungry grasshopper contacted a recumbent grass leaf and began to feed. Handling the leaf with the front tarsi, it consumed the entire leaf from tip to base. If the contacted leaf was upright, the grasshopper raised up on its hindlegs and pulled the leaf down with the front tarsi. In both cases the grasshopper fed while resting horizontally on the ground. Another hungry grasshopper contacted a cut leaf and ground litter as it crawled on the ground and fed on these items while handling them with the front tarsi.
On a dirt roadside, two IV instars were observed feeding horizontally on the ground. One fed upon a fallen seed of downy brome and the other on ground litter.
Several observations of feeding adults confined in a terrarium have been made. In addition to the feeding methods described above, adults have been seen to climb grasses to a height of 1/2 inch, cut through the stem, and consume the cut piece while holding onto it with the front tarsi. During the feeding bout, the hindlegs may be extended to rest on the ground. Although cut pieces are usually held and con sumed, they may occasionally fall to the ground. These are fed upon by the same individual after descending or by other individuals encountering them. Adults have been seen to feed on stubs of grasses or on short grasses, such as blue grama, from their normal horizontal position on the ground.
Two-choice tests using 10 species of plants have shown that adults of the mottled sand grasshopper preferred dandelion and downy brome. Second-choice plants included: needleandthread, western wheatgrass, blue grama, kochia, and alfalfa. Least preferred but ingested in small amounts were tumble mustard and common lambsquarters. Flixweed appeared to be least preferred, as it was only nibbled upon. The tests indicate that the mottled sand grasshopper, even though a polyphagous feeder, discriminates among available food plants.
Evidence of dispersal comes from collection of "accidentals" at high altitudes west of Boulder, Colorado. Resident populations occur at 6,700 feet near Boulder, while "accidentals" have been collected several times up to 12,200 feet, at a distance of approximately 22 miles from the nearest resident population. Whether the distance covered is by a single flight or by a succession of short flights and whether flights in other directions and distances are taken is unknown.
The nymphs are identifiable by their color patterns and external structures (Fig. 1-5).
1. Head with face nearly vertical, lateral foveolae triangular.
2. General color tan profusely spotted brown.
3. Instar I
(a) Pronotum with median carina strongly elevated; shallow notch in carina about one-third distance from posterior end.
(b) Hind femur with outer face fuscous for distal three-fourths, proximal one-fourth tan with brown spots. Hind tibia fuscous. Hind tarsus with first segment white, second segment fuscous, and third segment white except fuscous at distal end.
4. Instar II
(a) Pronotum with median carina strongly elevated; shallow notch in carina slightly more than one-third distance from posterior end.
(b) Hind femur with outer face tan and spotted fuscous; outer face often with two faint brown bands, one in middle, the other distal. Hind tibia usually orange, occasionally proximal end yellow.
5. Instars III, IV, V
(a) Pronotum with median carina strongly elevated and arcuate; deeply incised posterior to middle in III, anterior to middle in IV and V.
(b) Hind femur with outer face tan or gray, heavily spotted brown on chevron ridges and on lower and upper keels, two or three dark transverse bands often present. Hind tibia usually orange.
Two other species of Spharagemon with elevated median carina occur in the West. The nymphs of S. bolli and S. cristatum are probably similar to those of S. collare, but they have not been collected or studied. Adults of S. bolli are normally found in sunny meadows and openings of ponderosa pines and other woodlands. Adults of S. cristatum are found in the grasslands of Kansas, Oklahoma, Texas, eastern New Mexico, and southeastern Colorado.
Females ready to oviposit select bare areas of sandy soil close to vegetation. After completing oviposition and withdrawing her ovipositor from the soil, she covers the hole by brushing sand and soil litter over it with her hind tarsi. Males have not been seen attending ovipositing females. The whole act of oviposition was timed in Manitoba by Norman Criddle, an early investigator of grasshopper biology. Observations of two females revealed that they took 34 minutes to oviposit and produce 12 eggs per pod. This number is considerably less than that found in more recent research, indicating a wide range of clutch size. Pods of the mottled sand grasshopper are 3/4 inch long and 3/16 inch in diameter and contain from 21 to 28 eggs (Fig. 10). Eggs are tan and 5 to 5.2 mm long.
After sunrise, the grasshoppers gradually emerge from their shelters. They remain quiescent on bare ground or litter until the sun's rays strike them. Then they begin to bask by turning a side perpendicular to the sun's rays and by lowering the associated hindleg, which exposes the abdomen to the warming rays. During this period they often stir, preen, and turn around to expose the opposite side to the sun. The basking period may last for one to two hours before they start walking, feeding, and mating. They continue these activities for several hours until temperatures of the habitat become too hot for them, at which point they begin to stilt on bare ground (soil surface temperature 105°F). As temperatures increase further, they leave the bare ground and crawl into the shade of plants resting horizontally on ground litter.
In the afternoon when temperatures moderate, they again become active walking about, feeding, flying appetitively, and seeking mates. As temperatures in late afternoon cool further they bask again. When shadows engulf the habitat, the grasshoppers crawl into shelters under canopies of vegetation and rest horizontally on ground litter. Although temperatures are still relatively warm and within their normal activity range (70°F soil surface and 65°F 1 inch above ground), they are not easily flushed from their hide-outs. One may walk within a foot of them and they will not flush.
Cantrall, I. J. 1943. The ecology of the Orthoptera and Dermaptera of the George Reserve, Michigan. Misc. Publ. Mus. Zool., Univ. Michigan, No. 54.
Criddle, N. 1918. The egg-laying habits of some of the Acrididae (Orthoptera). Can. Entomol. 50: 145-151.
Gangwere, S. K. 1968. Relationships between the mandibles, feeding behavior, and damage inflicted on plants by the feeding of certain acridids (Orthoptera). Michigan Entomologist 1: 13-16.
Gangwere, S. K., F. C. Evans, and M. L. Nelson. 1976. The food-habits and biology of Acrididae in an old-field community in southeastern Michigan. Great Lakes Entomol. 9: 83-123.
Joern, A. 1982. Distributions, densities, and relative abundances of grasshoppers (Orthoptera: Acrididae) in a Nebraska sandhills prairie. Prairie Naturalist 14: 37-45.
Joern, A. 1986. Experimental study of avian predation on coexisting grasshopper populations (Orthoptera: Acrididae) in a sandhills grassland. Oikos 46: 243-249.
Otte, D. 1970. A comparative study of communicative behavior in grasshoppers. Misc. Publ. Mus. Zool., Univ. Michigan, No. 141.
Ueckert, D. N. and R. M. Hansen. 1971. Dietary overlap of grasshoppers on sandhill rangeland in northeastern Colorado. Oecologia 8: 276-295.
Next Species in Subfamily: Spharagemon equale
Previous Species in Subfamily: Metator pardalinus