American Grasshopper, Schistocerca americana
(Orthoptera: Acrididae)

Tha Amercian grasshopper is a common species found widely in the eastern United States, west to Iowa and Texas. In the southeast, it is one of the few species to reach epidemic densities. Adults fly readily and display a tendency to swarm. American grasshopper has two generations per year and overwinters in the adult stage. In Florida, eggs produced by overwintered adults begin to hatch in April to May, producing spring generation adults by May to June. This spring generation produces eggs that hatch in August to September. The adults from this autumn generation survive the winter. The eggs are clustered together in a whorled arrangement, and number 75 to 100 eggs per pod, averaging 85 eggs. The female inserts the egg pods into the soil up to a depth of about 4 cm and fills the upper portion of the oviposition hole with a frothy plug. Duration of the egg stage is two to three weeks. The nymphs, upon hatching, dig through the froth to reach the soil surface. Normally there are six instars. The young grasshoppers are light green in color. They are extremely gregarious during the early instars. At low densities the nymphs remain green throughout their development, but normally gain increasing amounts of black, yellow, and orange coloration commencing with the third instar. Development time is about four to six weeks, and then the adult can live for weeks or months. The adult is rather large, but slender bodied, measuring about 40 to 65 mm in length. A creamy white stripe normally occurs dorsally from the front of the head to the tips of the forewings. The forewings bear dark brown spots, while the pronotum has dark stripes.

American grasshoppers eat irregular holes in leaf tissue. Much of the feeding by adults occurs on forest, shade, and fruit trees. The nymphs, however, feed on a large number of grasses and broadleaf plants and both wild and cultivated corn is especially attractive to this species. When the population reaches a high density, it can strip vegetation of leaves. More commonly, grasshopper feeding results in plants with a ragged appearance. When the late-season crop of collards in the southeast U.S. is harvested mechanically, American grasshoppers may become incorporated into the processed vegetables. Although most grasshoppers can be kept from dispersing into crops near harvest by treating the periphery of the crop field, it is much more difficult to prevent invasion by American grasshoppers because they may fly over any such barrier treatments. Foliar applications of insecticides will suppress grasshoppers, but they are difficult to kill, particularly as they mature. Land management is an important element of population regulation. Grasshopper densities tend to increase in large patches of weedy vegetation that follow the cessation of agriculture or the initiation of pine tree plantations. In both cases, the mixture of annual and perennial forbs and grasses growing in fields that are untilled seems to favor grasshopper survival, with the grasshoppers then dispersing to adjacent fields as the most suitable plants are depleted. However, as abandoned fields convert to dense woods or the canopy of pine plantations shades the ground and suppresses weeds, the suitability of the habitat declines for these grasshoppers.

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American grasshopper, Schistocerca americana.
(Photographer: J. Capinera, University of Florida)

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American grasshopper, Schistocerca americana, nymphs.
(Photographer: J. Capinera University of Florida)

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