Synonyms and other taxonomic changes
Pezotettix aridus Scudder, 1878. Type locality: Buchanan, Arizona
Melanoplus aridus (Scudder) Scudder, 1897
Melanoplus tristis Bruner, 1904. Type locality: Durango Colorado
Melanoplus desultorius Rehn, 1907. Type locality: Carr Canyon, Huachuca Mountains, Arizona
Melanoplus desultorius insignis Hebard, 1917. Type locality: Copete Mine, 30 mi E of Carbo, Sonora, Mexico
Explanation of Names
It is possible that there are more than one species included here, but it's difficult to draw lines if there are.
Melanoplus desultorius is frequently treated as a distinct species, but there seems to be no reliable way to separate all individuals into this species or into M. aridus. The supposed distinctions of slightly different male cerci, smaller size, and narrower wings of M. aridus do not seem to hold up, and gray individuals (aridus) can sometimes be found mating with colorful red-eyed individuals (desultorius).
The two might be separable based on coloration and average differences in measurements, but it seems that M. desultorius probably represents optimal development in concert with a regional variation in coloration.
Depauperate individuals from high elevations in the Four Corners region and across northern Arizona have been called a separate species (Melanoplus tristis) by some authors. However, the only distinction seems to be small size, and most authors have treated it as a synonym.
The species (or species complex) shows much regional variation in both size and in coloration; see comments under Remarks below.
Smallish (mostly under 1 inch, but sometimes longer in the south). Antennae and eyes are usually brown, often strongly reddish. With very short wings, and the tegmina oval and usually widely separated. The bar behind the eyes on the sides of the pronotum is usually wide at the front, with an included pale spot, but narrows to a slightly up-bowed dark line at the top edges of either side of the mesonotum (rear part of the pronotum). There is usually a distinct (often very narrow, at least toward rear) dark stripe down the middle of the top of the pronotum. The abdomen usually has at least indications of two dark bands (often broken) extending back along either side of the top, and often a second pair of dark lines running just above these. The underside is usually yellowish. Hind tibia are blue, usually with blue or yellow on the lower half of the "knee" of the femur as well. Hind femur is usually mostly light brownish or yellowish on the outer side (more often grayish west of Arizona).
Male with end of abdomen not unusually enlarged; with subgenital plate evenly curved around the top edge; with fuculae well-developed, slender, longer than wide; cerci long and very slender, not pointed, usually bent in and up a bit and often very slightly swollen toward the tip, widening at the base.
Texas to Kansas and westward into California.
Highly varied, from low desert and grasslands well up into the mountains. Mostly open dry exposed areas where food plants are found.
Mostly Composites in the Aster Tribe, but sometimes other Composites or plants in other families.
Eggs overwinter. Adults late spring to frost.
In the east (roughly east of the Rio Grande), individuals often have a gray appearance, but with much yellow, and with bold narrow black dark markings. West from the Rio Grande in the south they average more stocky and often more colorful (but not all individuals are equally colorful) with richer blues and yellows dominating the body and with reddish eyes (these were named M. desultorius). On the Colorado Plateaus and into the Southern Rockies, coloration tends to be dull grays and browns, and size is often extremely small (M. tristis). In the Great Basin, Mojave and Colorado Deserts they average a bit more slender, and most often light gray with dark markings narrow and less developed; the hind femora are often strongly banded. In mountains of the Gila drainage they are often boldly patterned with heavy dark markings.
It seems that they look just a bit different in most any region where they are found.