Wyoming distribution map
The little spurthroated grasshopper has a wide geographic range in Western North America. It occurs in grasslands, often as the dominant grasshopper, from the Canadian provinces to northern New Mexico. It is common in clearings of montane coniferous forest and in the parklands of the Canadian northern forest. In Colorado, it is found in montane grasslands as high as 10,000 feet. Its northern geographic range and its distribution in montane habitats indicate tolerance for colder temperate climates and intolerance for warmer conditions.
Large populations infest regions of bunchgrass-sagebrush in Idaho where densities may reach 20 to 40 per square yard in outbreak years. This species confined in field cages on western wheatgrass in Montana, caused a loss of 35 mg dry weight of forage per adult grasshopper per day. This amount was less than that caused by an adult big-headed grasshopper, Aulocara elliotti, which caused a loss of 62 mg per day. The reason for this difference is no doubt related to the difference in weight of the two species. The larger grasshopper, which requires more food, caused the greater damage. Unconfined in its natural habitat, the little spurthroated grasshopper may be even less damaging because it feeds on forbs as well as grasses.
Even though results from the field indicate that the little spurthroated grasshopper is a polyphagous feeder, laboratory tests of food preference show that it discriminates between paired species of plants. It prefers dandelion to blue grama, western wheatgrass, and alfalfa, but it eats equal amounts of dandelion and downy brome.
No field observations have been made of how this grasshopper attacks a food plant; however, several observations have been made of its feeding in a laboratory terrarium. In feeding on needleandthread grass, a hungry female crawled on the soil surface until she contacted the food plant. She then reached up and cut a green leaf about one-half inch above the ground level and held onto the cut section, approximately 1 to 2 inches long, with the front tarsi and consumed the entire section from the cut end to the tip. She repeated this procedure five times on leaves of the same plant. The sixth time she cut another leaf but did not continue feeding, probably having been satiated. Adults were also observed feeding on ground litter such as fallen leaves of needleandthread and scarlet globemallow. In their natural habitat in Montana, adults have been observed feeding on ground litter.
Evasive flights of the little spurthroated grasshopper are straight, silent, and low (4 to 9 inches above ground), and for short distances (3 to 10 feet).
The nymphs are identifiable by their structures, color patterns, and shape (Fig. 1-5).
1. Head with face nearly vertical; frontal ridge distinctively black (Fig. 8), vertical black band running from bottom of compound eye down to mouthparts. Antennae filiform, each segment ringed anteriorly in white. Compound eye brown with many light spots.
2. Cream-colored crescent beginning on gena below compound eye and running onto lateral lobe. Dorsal stripe of hind femur usually interrupted near middle by cream-colored band. Hind tibia pale yellow or pale gray, front edge fuscous.
3. Body color is cream and tan with fuscous lines and marks. Bottom of thorax and abdomen usually white, occasionally pale yellow.
Many of the described nymphal characters of M. infantilis, M. gladstoni, and M. occidentalis are similar, yet nymphs of these species can be separated easily by color and by their seasonal appearance. The venter (ventral side of both thorax and abdomen) of nymphs of M. infantilis is usually white, while the venter of nymphs of M. gladstoni is usually bright yellow and of M. occidentalis pale gray. Nymphs of M. infantilis and M. occidentalis are present in the grasshopper assemblage early in the season along with nymphs of M. sanguinipes and M. packardii, while those of the M. gladstoni are present late when all four of the former species are adults.
On South Dakota rangeland, females have been observed ovipositing to a depth of 1 inch in clumps of buffalo grass. Caged females oviposit readily into bare soil. Upon withdrawing their abdomen, females brush soil and litter over the exit holes with their ovipositor. The pods are curved, seven-eighths to 1 inch long, and contain 10-13 light tan eggs in the bottom half (Fig. 10). The eggs are 3.9 to 4.2 mm long. The top half of the pod consists of dry froth. There is one generation annually.
Both nymphs and adults began to bask about one hour after sunrise by sitting horizontally on bare ground or on the crown of blue grama grass. At this time, temperatures of the soil surface and at 1 inch high were below 60°F. They turned one side perpendicular to the rays of the sun and often lowered the exposed hindleg to the ground. They frequently stirred and raised and lowered their flexed hindlegs during basking. Adults were observed basking till 10 a.m. when soil surface temperature was 80°F. and air temperature 1 inch above the ground was 68°F. Exactly when these grasshoppers start morning activities has not been determined.
Two fifth instar nymphs were observed in the afternoon sitting vertically head up, 2 inches high on the leaves of needleandthread grass when soil surface temperature was 115°F. This behavior was ostensibly to escape ground heat.
Brusven, M. A. 1972. Differentiation and ecology of common Catantopinae and Cyrtacanthacridinae nymphs (Orthoptera: Acrididae) of Idaho and adjacent areas. Melanderia: 9: 1-29.
Hansen, R. M. and D. N. Ueckert. 1970. Dietary similarity of some primary consumers. Ecology 51: 640-648.
Hewitt, G. B. 1978. Reduction of western wheatgrass by the feeding of two rangeland grasshoppers, Aulocara elliotti and Melanoplus infantilis. J. Econ. Entomol. 71: 419-421.
Kemp, W. P. and J. A. Onsager. 1986. Rangeland grasshoppers (Orthoptera: Acrididae): Modeling phenology of natural populations of six species. Environ. Entomol. 15: 924-930.
Lockwood, J. A., J. C. Burne, L. D. DeBrey, R. A. Nunamaker, and R. E. Pfadt. 1990. The preserved fauna of grasshopper glacier (Crazy Mountain, Montana): Unique insights to acridid biology. Boletin de Sanidad Vegetal, Fuera de Serie No. 20: 223-236.
Onsager, J. A. and G. B. Hewitt. 1982. Rangeland grasshoppers: average longevity and daily rate of mortality among six species in nature. Environ. Entomol. 11: 127-133.
Pfadt, R. E. and R. J. Lavigne. 1982. Food habits of grasshoppers inhabiting the Pawnee site. Wyoming Agr. Exp. Stn. Sci. Monogr. 42.
Pooler, P. D. 1989. Factors influencing grasshopper oviposition site selection on South Dakota rangelands. M.S. thesis, South Dakota State University, Brookings, SD.
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