GRASSHOPPERS OF NEW MEXICO

HOW TO USE THIS MANUAL

Grasshoppers of New Mexico Contents

This manual contains sections on ecology, economics, and history; family, subfamily, generic and species keys; species descriptions; distribution maps, line drawings, and color photographs. We suggest that the reader first become familiar with the illustrations and range maps, making identification easier, more efficient, and probably more accurate. The reader may try to match specimens with the photographs as a quick means of identifying some of the more distinctive species; the reader may also want to compare specimens, particularly nymphs, with photographs shown in Pfadt's circulars (1988-1991ff.). If the specimen does not match any of the species in any of the photographs, then use the detailed keys in this manual. Refer to the glossary for definitions of anatomical terms used in the keys.

For those readers who have never used a key before: Notice that the keys are written like a road map with a decision to be made at every fork. Start with the first couplet, read both parts carefully, study the specimen in hand, and determine which couplet the specimen resembles more closely. Most of the time there will be a number at the end of the chosen couplet to direct you to the next set of descriptions for consideration. Write the numbers of the couplets used in particular identifications on a piece of scratch paper; in case of error or confusion, this makes retracing steps in the identification process easier.

Before any of the keys can be used, you must capture grasshopper specimens. Some grasshoppers are good flyers, but most can be collected with an aerial insect net after a little practice. If you have no net and wish to purchase or make one, contact your county Extension agent for sources or patterns. The most effective technique is to stalk the grasshopper and drop the net over it when it is still. If it flies away, stalk it again, trying to approach it from the rear. Some grasshoppers can be collected using a sweep net (a heavier net used for making wholesale collections of many kinds of insects from plants); some may even be caught by hand.

Use a killing jar to kill grasshoppers. Contact your county agent for instructions on making and using a killing jar. Specimens may also be killed by placing them in the freezer overnight (sometimes longer). Do not use alcohol to kill or store grasshoppers, as this fluid will discolor the specimens and cause an unnatural extension of the hind legs.

Specimens (especially large ones) that are be retained for a collection are often gutted with fine scissors and their internal organs replaced with cotton dusted with talcum powder and boric acid. Grasshoppers are pinned through the right side of the prothorax with standard insect pins. Pinned specimens are then stuck into a box with a pinning surface. For display and especially for identification, those with colorful or banded hind wings are usually spread on the left side either while the specimen is fresh and pliable or after it has been relaxed in a humidifier chamber. (Your county agent will have publications with more information on collecting insects.) Where quick and accurate identification is essential, grasshoppers can be frozen, wrapped in dry tissue, and packed into a mailing cylinder or sturdy cardboard box to be mailed to Extension specialists or county agents, or NMDA personnel.

Sometimes it is necessary to determine a grasshopper's sex, especially to use the key to the genus Melanoplus. Male grasshoppers usually have prominent cerci that project up on each side of the subgenital plate (Fig. 1). The tip of the male abdomen is rounded, wherein the female usually has four pointed sclerotized valves projecting from the posterior end (Fig. 1).

Because nymphs are difficult to identify accurately, use only adult grasshoppers for identification using the keys. As a general rule, adult grasshoppers have two pairs of wings, while nymphs have no wings or only wing pads (wings develop externally in grasshoppers). However, adults of some flightless grasshopper species naturally have no wings or only short ones. To distinguish between adults and nymphs, note that in adults the tegmina (or forewing pads) are above the hind wings, whereas in immature specimens the reverse is true.

The authors have strived to include all currently recognized species of grasshoppers based on specimens in the various insect collections listed in the acknowledgments. A very few species for which we have seen no specimens, but for which range data indicate should be found in New Mexico, are included in both the text and keys. A few species, especially of Melanoplus, have been reported from New Mexico that may be accidental introductions or misidentifications. These are not included in the current work but may eventually prove to be valid records. As with any systematic treatment of an insect taxon as diverse as the grasshoppers, there are some specimens in our collections that are apparently undescribed species; these specimens and "species concepts" are not mentioned further in this manual but would, of course, be considered in later revisions if the species are formally described. Finally, there are several scientific names for supposedly New Mexico grasshoppers that are controversial: Melanoplus fluviatilis Bruner is one of these. Its close resemblance to M. foedus Scudder except for fine details in body texture and habitat preferences suggest that, in view of present available evidence, fluviatilis may not be a valid species in New Mexico.

Grasshoppers of New Mexico Contents