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Guide to Common Western Grasshoppers Introduction | External Anatomy | Names and Species | Grasshopper Populations | Life Cycles | Seasonal Occurrence and Behavior | Collections and Survey | Grasslands of North America | Food Plants | Glossary | Selected References | Species Fact Sheets | (PDF) For some time, supervisors and grasshopper scouts have desired a practical means of identifying common species of grasshoppers in both nymphal and adult stages. The consensus of ideas of APHIS and ARS personnel focused on a field guide that would picture in color not only the adults but also all nymphal instars. In addition the guide should include pictures of diagnostic features of each species. Treatment of 50 species was originally contemplated, but the number increased to 70 as more consideration was given to the species of grasshoppers frequently encountered by scouts working in the 17 western states. Names of 70 species (mainly Acrididae, a few Tettigoniidae) were selected by the technical committee of the Grasshopper Integrated Pest Management Project (USDA 1987-94) and are listed in the project outline of the field guide. From this list the author chose six to twelve species to work on annually. Selection was made on the basis of availability of grasshopper species and of site proximity. Because new employees often need instruction on grasshopper structure, life history, behavior, and ecology, an introduction covering these subjects was also proposed. The project originally was estimated to be completed in two years but it was soon realized that more time was needed. The first species chosen were common, abundant ones inhabiting sites close to Laramie. As fact sheets on these species were completed, sites farther from Laramie chosen for other common grasshoppers entailed more travel time and left less time for productive work. The paucity of published information on the less researched species and less unpublished data in files of the author required first-hand laboratory and field observations. Another problem encountered was the low densities of certain otherwise common species over the last five years, making observation and collection of live specimens more difficult. In spite of these impediments the publication of two new fact sheets in 1994 brings the total number of species treated to 39. We are gathering data and photographing additional species in the summer of 1994. Completion of fact sheets on these will bring the total number to 50. The need for additional copies of the Field Guide to Common Western Grasshoppers for inclusion in the User Handbook of the Grasshopper Integrated Management Project has provided the opportunity to revise and to add new subjects to the introductory bulletin. These subjects include the following:
The production of this Field Guide to Common Western Grasshoppers has required the efforts and expertise of several staff members of the University of Wyoming. I wish to acknowledge their valued contributions that made this publication possible and the contributions of the professionals of Frontier Printing, Cheyenne, Wyoming.
I gratefully acknowledge the assistance of Shanna Breeding, Mark Carter, Donald Hostetter, Boris Kondratieff, John Larsen, Tim McNary, Bill Elliott, Bruce Shambaugh, Robert Stuckey, and David Weissman in locating species of grasshoppers and providing specimens, and the help of Burrell E. Nelson of the Rocky Mountain Herbarium in identifying plants. I also wish to acknowledge the peer review of the manuscript by my colleagues Jeffrey C. Burne, E.W. Evans, Robert J. Lavigne, Jeffrey A. Lockwood, and Bruce Shambaugh. Funding for the publication of the Field Guide to Common Western Grasshoppers was provided through a grant to the University of Wyoming from the U.S. Department of Agriculture's Animal and Plant Health Inspection Service (APHIS)/Grasshopper Integrated Pest Management Project. The university and author gratefully acknowledge the support of APHIS, which made this publication possible. College of Agriculture • The University of Wyoming Steve W. Horn, Director, Agricultural Experiment Station, University of Wyoming, Laramie 82071. Persons seeking admission, employment or access to programs of the University of Wyoming shall be considered without regard to race, color, national origin, sex, age, religion, political belief, disability, veteran status and marital or familial status. Persons with disabilities who require alternative means for communication or program information (braille, large print, audiotape, etc.) should contact their local UW Extension Office. To file a complaint, write the UW Employment Practices/Affirmative Action Office, University of Wyoming, P.O. Box 3354, Laramie, Wyoming 82071-3354 Information given here is supplied with the understanding that no discrimination is intended and no endorsement by University of Wyoming Agricultural Experiment Station is implied on trade or brand name commodities. Nearly 400 species of grasshoppers are known to inhabit the 17 western states. Of these, approximately 70 species are common enough to be encountered regularly by persons scouting for damaging populations. For personnel who lack taxonomic experience, identifying the nymphs and adults of these common grasshoppers is difficult. Yet the need for considering species in control decisions becomes ever more urgent. Control officials need to know both the identities and the densities of species composing infestations to assess accurately the economic threat and select prudent solutions. There are several reasons why it is necessary to correctly identify species. (1) Species vary in their biotic potential and in their capacity for causing damage. (2) Depending on their food habits, species may be either pests or beneficials. (3) Certain species of pest grasshoppers are highly migratory and often pose a serious threat to distant crops. (4) Species vary in their seasonal cycle (period of hatching, development, and reproduction), which in turn affects the timing of control treatments. (5) Because current chemical and biological methods of controlling grasshoppers are more sophisticated, their effective use requires greater knowledge of the pests' life histories and habits. (6) As environmental impacts of control are more finely evaluated, recognition of pest species of grasshoppers has become essential in the selection of management strategies. The purpose of this manual is to provide a pictorial guide that will allow plant protection personnel to make grasshopper identifications in the field. Although the surest method for obtaining an accurate identification is submission of the specimen to a specialist, this procedure is not feasible during an expeditious grasshopper survey. To achieve the requisite efficiency in making a useful survey, the scout must be able to identify, and in a short time learn to recognize on sight, the common species inhabiting the infested area. Grasshoppers are relatively large insects with quite distinct appearances. Diverse traits permit one to identify a specimen of an unknown species by comparing it with identified museum specimens. One may also identify the specimen by comparing it with good color pictures. When accompanied by illustrations and descriptions of distinguishing characters and their variations, color pictures are probably the best means of accurate identification of an unknown specimen (short of submitting it to a specialist). This Field Guide to Common Western Grasshoppers provides the scout with color pictures of the nymphs, adult male, and female, and illustrations and descriptions of distinguishing characters allowing comparisons with unknown specimens that need identification. The guide also contains distribution maps of species, brief accounts of their seasonal cycles, feeding and reproductive behavior, and habitat preferences. All may serve as additional clues to the identities of specimens as well as provide pertinent information for grasshopper management. Introduction | External Anatomy | Names and Species | Grasshopper Populations | Life Cycles | Seasonal Occurrence and Behavior | Collections and Survey | Grasslands of North America | Food Plants | Glossary | Selected References | Species Fact Sheets | (PDF) |
