Preface

For some time, grasshopper scouts and super- visors 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 The paucity of published information on the less researched species and less unpublished data in files of the author required first-hand laboratory and field observations.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 in recent years, making observation and collection of live specimens more difficult. In spite of these impediments the publication of four new fact sheets in 2002 brings the total number of species treated to 60.

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:

• Embryonic development and diapause of grasshoppers

• Behavior of grasshoppers

• Additional instructions for collecting and preserving grasshoppers

• Instructions for shipping live grasshoppers

• Inclusion of a map delineating western grasslands

• Table of common-scientific names of grasshopper food plants

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Acknowledgments

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.

• Elizabeth A. Donahue, graphic artist

• Dana Lynn Dreinhofer, publications editor

• Kim Gould, publications editor

• Norma Hoshor, word processor

• Shannon Jaeger, publications editor

• Herbert D. Pownall, photographer

• Elizabeth Ono Rahel, graphic artist

• Karen D. Singer, typist

• William L. Stump, artist

• Ellyn Sturgeon, word processor

I gratefully acknowledge the assistance of Greg Abbot, Shanna Breeding, Mark Carter, Donald Hostetter, Boris Kondratieff, John Larsen, Tim McNary, Bill Elliott, Scott Schell, Spencer Schell, 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. Dr. Lockwood peer reviewed all 60 grasshopper fact sheets. I also wish to acknowledge the encouragement and financial support in recent years of Steve W. Horn, dean, University of Wyoming College of Agriculture: James J. Jacobs, director, Wyoming Agricultural Experiment Station; Thomas Thurow, head of the Department orf Renewable Resources, and Larry Munn, former head, to continue the research and the publication of grasshopper fact sheets.

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
Francis D. Galey, dean, College of Agriculture, University of Wyoming, Laramie 82071.

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Introduction

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.

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