• Topics: Entomology and Nematology  | Grasshoppers  | Landscape Grasshopper and Cricket Pests  | Squitier, Jason M (student)  |  Featured Creatures collection  | Family: Acrididae 

American grasshopper, Schistocerca americana (Drury) (Insecta: Orthoptera: Acrididae)¹

Introduction

The American grasshopper can cause serious damage to Florida crops. Injurious outbreaks occur in fields where the adult grasshoppers invade daily from their roosting sites in nearby trees and shrubs. The nymphs may also walk to the fields, and eggs are even deposited within the crops.

Distribution

The American grasshopper can be found throughout Florida. In North America, its range is defined as east of the Great Plains and south of the fortieth latitude mark which encompasses the states of Kentucky, Tennessee, Mississippi, Alabama, Georgia, North and South Carolina, and Virginia. This grasshopper's range also includes the Bahamas and Mexico.

Description

Egg: The female American grasshopper deposits her eggs in the soil about 2 to 3 cm below the surface by pushing her ovipositor down into the substrate (Figure 1). The grasshoppers prefer areas with some ground cover to deposit their egg clusters. The egg cluster generally consists of 60 to 80 eggs which are secured together by a frothy polymer-like substance that the female secretes. Females may lay up to three egg pods. The eggs are 7 to 8 mm in length and are light orange in color.

Figure 1. 

Female grassshopper laying eggs.

Nymphs: The nymphs (Figure 2) hatch from the eggs in three to four weeks and must work their way to the surface. The nymphs go through five or six stages before reaching adulthood. Six instars are normal, but if densities are low only five instars will be completed. If there is a high density of nymphs the latter instars will be more yellow, orange balck, than green; at low densities, nymphs may be completely green. The developmental stages of the wings (from no wing, to a wing pad, to more developed wing pads, and finally wings) is the easiest identifier to determining the instars. The first instars are pale green with a black middorsal stripe running the length of the body. The first instar is 6 to 7 mm in length and has 13 antennal segments. Wing pads appear in the second instar as well as the addition of four more antennal segments. The changes in the 3rd instars are a length of 16 to 18 mm, 21 to 22 antennal segments and the wing pads take on a triangular shape. In the fourth instar wing venation becomes present and the antenna has 22 to 24 segments. In the fifth instar the orientation of the wing pads changes from ventral to posterior. This means that the wings now point horizontally instead of vertically toward the ground. The fifth instar will also have a length of 27 to 30 mm and 24 to 25 antennal segments. The sixth will be 35 to 45 mm in length and have 25 to 26 segments in its antenna.

Figure 2. 

Nymph of American grasshopper, Schistocerca americana.

Adult: Adults are recognized by the appearance of fully developed wings with distinctive brown spots on them, and a color change from the nymphal green to a reddish brown with a light yellow middorsal stripe extending from the head to midway on the tegmina (wings). The length of the male is 39 to 42 mm, whereas the female is 48 to 55 mm. The overall color gradually changes from a reddish brown to more of a yellowish brown hue as the grasshopper reaches sexual maturity.

Figure 3. 

Adult American grasshopper, Schistocerca americana.

Life Cycle

The American grasshopper has two generations a year and overwinters in the adult stage, unlike most grasshoppers whose eggs survive the winter. Thus, American grasshoppers are present throughout the year. The two hatching periods are from April to May, and again from August to September.

Damage

The American grasshopper can cause injury to corn, oats, rye, peanuts, sugarcane, tobacco, cotton, vegetables, and citrus (Figure 4). The American grasshopper has received much attention in Florida for its defoliation of young citrus trees. The plants are damaged by the grasshopper gnawing on the leaves. Some young vegetables can be eaten to the ground. Most of the feeding damage is caused by the third, fourth, and fifth instars. Those three stages have a much larger appetite than the adults. Aside from commercial crops the American grasshopper shows a preference for bahiagrass, bermudagrass, dogwood, hickory, crabgrass, woodsgrass and nutgrass.

Figure 4. 

Adult American grasshopper, Schistocerca americana.

Sampling

Grasshopper densities are estimated in two ways. The first is to select a plot and determine its relationship to the rest of your acreage. The area can then be walked and the number of grasshoppers that leap or fly should be counted. The second method is to sweep the plot area with a sweep net to determine the average grasshopper population. The latter technique is a relative assessment that is only useful for distinguishing "high" from "low" density areas.

Management

Biological Control

The biological controls known for the American grasshopper affect the population on a small scale. Blister beetle (Coleoptera: Meloidae) larvae, which develop in the soil, consume grasshopper eggs. Grasshoppers also fall prey to a number of birds. Cattle egrets consume large numbers and to a lesser extent so do robins, mocking birds and crows. Grasshoppers are sometimes parasitized by other insects. The larvae of flies (Diptera: Sarcophagidae and Tachnidae) have been found in grasshoppers. The fungi Beauveria bassiana and Metarhizium flavoviride are currently being tested for biological control.

Cultural Control

Disking and plowing are two good ways to destroy grasshopper eggs and it also kills small nymphs. In citrus groves, clean cultivation acts as a deterrent to oviposition and it reduces the number of newly hatched nymphs. The time of cultivation is very important. If cultivation is done too late the grasshoppers may actually be driven to the crops for a source of food. In Florida, young pine plantations in which weed control is not practiced, have yielded high levels of grasshoppers. These grasshoppers have been known to affect crop plants that are near the boundaries of the pine farms. A continuous weed suppression program would avoid this problem.

Chemical Control

It is best to apply insecticide before the grasshoppers are adults because it is easier to kill the nymphs. For specific insecticide recommendations consult the product label or the relevant Florida Insect Management Guide:

Insect Management Guide for Citus (http://edis.ifas.ufl.edu/CG055)

Insect Management Guide for Field Crops and Pastures (http://edis.ifas.ufl.edu/TOPIC_GUIDE_ IG_Field_Crops_and_Pastures).

Insect Management Guide for Sweet Corn (http://edis.ifas.ufl.edu/IG158)

Selected References

Capinera, JL 1993. Differentiation of nymphal instars in Schistocerca americana (Orthoptera: Acrididae). Florida Entomologist 76:176 - 179.

Capinera, JL 1993. Host-plant selection by Schistocerca americana (Orthoptera: Acrididae). Environmental Entomology 22:127 - 133.

Capinera, JL, Scherer CW and Squitier JM (September 1999). Grasshoppers of Florida. UF/IFAS. Available: http://entnemdept.ifas.ufl. edu/ghopper/ghopper.html (5 September 2001).

Dakin, ME, and KL Hays.1970. A synopsis of Orthoptera (Sensu Lato) of Alabama. Auburn University Agricultural Experiment Station Bulletin 404, p.49.

Griffiths, JT, and WL Thompson. 1952. Grasshoppers in citrus groves. University of Florida Agricultural Experiment Station Bulletin 496:1 - 26.

Knapp, JL, TR Fasulo, and RF Brooks. 1987. Florida Citrus Integrated Pest and Crop Management Handbook section 11, p.3.

Kuitert, LC and RV Connin. 1953. Grasshoppers and their control. University of Florida Agricultural Experiment Station Bulletin 516.

Kuitert LC and , Connin TV. 1952. Biology of the American grasshopper in the southeastern United States. Florida Entomologist 35:22-33.

Milne, L and Milne, M 1995. National Audubon Society field guide to North American insects & spiders. Alfred A. Knoph, Inc. New York. p. 425-426.

Mizell RF, Fasulo TR, Short DE. (2002). WoodyBug: pest and beneficial arthropods of southeastern U.S. woody ornamentals. UF/IFAS. CD-ROM. SW 119.

Thomas, MC. 1991. The American grasshopper, Schistocerca americana americana (Drury) (Orthoptera: Acrididae). Division of Plant Industry Circular 342.

Wilkerson JL, Webb SE, Capinera JL. (2005). Vegetable Pests II: Acari - Hemiptera - Orthoptera - Thysanoptera. UF/IFAS CD-ROM. SW 181.

The Institute of Food and Agricultural Sciences (IFAS) is an Equal Opportunity Institution authorized to provide research, educational information and other services only to individuals and institutions that function with non-discrimination with respect to race, creed, color, religion, age, disability, sex, sexual orientation, marital status, national origin, political opinions or affiliations. For more information on obtaining other extension publications, contact your county Cooperative Extension service.

U.S. Department of Agriculture, Cooperative Extension Service, University of Florida, IFAS, Florida A. & M. University Cooperative Extension Program, and Boards of County Commissioners Cooperating. Millie Ferrer-Chancy, Interim Dean.

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