A wealth of knowledge concerning grasshopper biology and ecology, damage potential and control practices is available to anyone with the interest and the ability to search through entomological literature. The searcher will quickly note, however, that grasshoppers differ significantly in their biological attributes, damage potential and susceptibility to management. Hence, field workers must be able to identify grasshoppers, or the abundance of specific information on grasshoppers is practically useless.

Believing that grasshopper identification is the key to knowledge concerning grasshoppers, we provide a dichotomous key to the adult grasshoppers known or thought to occur in Colorado. The illustrated key presented here is adapted from Alexander (1941); it is revised extensively although the original format is retained.

Compared to some other groups of insects, grasshoppers are not difficult to differentiate. Nevertheless, the user will encounter some problems with grasshopper identification. In some groups, differentiation is based on only one sex. Thus, identification of Melanoplus spp. and some others requires male specimens. Similarly, nymphs are difficult to identify, and no attempt is made here to include them in this key. These problems do not represent oversights on our part; rather, they represent the state of the "art." We have attempted to avoid use of color in this key because grasshopper color changes as specimens dry. Sometimes color use cannot be avoided, and where color characters are reliable, as in hind tibia color, we have used it extensively. We have not included subspecies designations in the key.

Anyone attempting to identify grasshoppers will find it much easier if several or many specimens of the same species are available. Individual specimens may be extremely difficult to identify because of the inherent variability within and among populations. Thus, when collecting specimens for identification, extensive collections should be made.

Grasshopper classification is constantly in a state of flux since universal agreement on subfamily, genus and species does not exist. We have attempted to provide current information but recognize that changes probably will occur in the near future. Also, some genera (Trimerotropis in particular) have not been examined critically since the early 1900s, and some species probably are only subspecies exhibiting significant geographic variation.

Additional useful information on identification of grasshopper species can be obtained in Otte (1981; Gomphocerinae and Acridinae of North America); Strohecker et al. (1968; California); Hewitt and Barr (1967; Oedopodinae of Idaho), Ball et al. (1942; Arizona); Beamer (1917; Oedopodinae of Kansas); Claassen (1915; Melanopli of Kansas); Coppock (1962; Oklahoma); and Pfadt (1965; Wyoming).

Note that individual drawings of wings and tegmina are right wing and tegmen and are shown in spread position. The only exception is figure 1, which shows left wing and tegmen in spread position. An overview of grasshopper anatomy and the relationships of various segments are shown in figures 1-5.

Key to Stages of Grasshopper Development
Separation of Adult Grasshoppers (Acrididae) from Related Insect Families Found in Colorado
Grasshoppers of Colorado Contents

Figure 1- Top view of adult grasshopper.

Figure 2- Side view of adult grasshopper.

Figure 3 - Front view of grasshopper head. Figure 4 - Bottom view of grasshopper thorax.

Figure 5A - Side view of male abdomen tip. Figure 5B - Subgenital plate of male pulled back to show aedeagus.

Figure 5C - Top view of male abdomen tip. Figure 5D - Side view of female abdomen tip.

Key to Stages of Grasshopper Development
Separation of Adult Grasshoppers (Acrididae) from Related Insect Families Found in Colorado
Grasshoppers of Colorado Contents