Species Melanoplus fluviatilis - Sandbar Grasshopper

Southern populations in Texas and Oklahoma (named "isleyi") tend to be yellowish in body color with the hind tibiae most often buff to yellowish (but they may be other colors) and the postoccular bars of the pronotum usually weak and poorly developed. Populations westward and northward (named

"fluviatilis") tend to be browner or grayer with well-defined dark postocular bars, and with hind tibial color more often of brighter and varied colors. In northern Oklahoma and southern Kansas the "isleyi" and the more typical "fluviatilis" intergrade freely, and cannot be divided as different species. The name isleyi should be treated as a subspecies of M. fluviatilis, but this combination has never been published.

M. fluviatilis (including isleyi) occurs in a habitat usually apart from its near relatives M. packardii and M. foedus, but occasionally they occur side by side, yet remain totally distinct. Since coloration is distinctly different, living specimens are rarely difficult to distinguish, though discolored museum specimens of M. fluviatilis and M. foedus can be difficult to separate since there seems to be no reliable and constant morphological difference.

Structurally the same as M. foedus with practically identical reproductive structures and external morphology, but colored differently, with the dorsum of the pronotum usually plain (lacking pale lateral stripes) and with the overall coloring more dull (less shiny). North from Oklahoma the dark postocular bar (behind the eyes on head and upper sides of pronotum) is usually strongly developed and typically nearly black. Hind femur barred dark above, internally, and often on the outer face; usually reddish ventrally and on the inner side. Hind tibiae varied in color (buff, yellowish, green, blue, red, purple, etc.), often within the same population, rarely even with right and left hind tibiae of different colors.

Where they occur together, M. foedus (almost) always has pink to red hind tibiae; the outer face of the hind femur is usually plain or nearly so (most often yellowish) with the ventral side and the inner face usually yellowish; has pale stripes laterally on the dorsum of the pronotum; dark postoccular bars are usually poorly developed or even absent and never dark; and favors more oppen sandy grassland habitats. M. foedus is more similar in coloring to M. packardii, than to M. fluviatilis, but is usually more yellowish or orangey in hue with less developed dark markings than seen on either M. packardii or M. fluviatilis. As a rule of thumb, in a given area, M. foedus is the largest of the three, but this is not constant enough to be a reliable distinguishing trait.

M. packardii has different internal male genitalia from M. foedus & M. fluviatilis, but in coloring it is much like M. foedus, differing in the same ways from M. fluviatilis. As compared to M. foedus, it is usually darker with more developed dark postoccular bars (but rarely black), more grayish to olivaceus in overall coloring, and in areas of overlap most often with hind tibiae blue, but other colors may predominate in some areas (especially red). From M. fluviatilis it differs in having the pale lateral stripes on top of the pronotum prominent, and only rarely has distinct bars across the outer face of the hind femur. Usually the lower edge and inner face of the hind femur not strongly reddish. It also favors open non-riparian habitats, but otherwise is something of a generalist (though favoring areas of heavier or rocky soils).

M. fluviatilis might be confused with dark/dull colored individuals of M. angustipennis, and they commonly occur together, but M. fluviatilis is larger and stockier, and usually of a more dull coloring than is M. angustipennis. Males of M. angustipennis have longer furculae, and sometimes have a notch at the tip of the subgenital plate.

M. fluviatilis is sometimes similar to M. differentialis in appearance (particularly in Texas and Oklahoma), but that species is larger, and has the distinct black herringbone pattern on the hind tibia.

Known from Wyoming, Nebraska, Minnesota, and Illinois, south to central Texas, and west to the Rockies in eastern Colorado and the Rio Grande in central New Mexico.

Primarily along riparian corridors of streams, rivers, and other drainages, and near the shores of lakes; often but not exclusively where soils are sandy. Occuring most often among open deciduous brush or tall herbaceus growth, often along the edges of and in openings within riparian forest, or on sandbars within the channel. Colonies tend to be localized by habitat preference, and sometimes far between.

Tends to favor tall herbaceus and shrubby dicots, and apparently fond of Legumes (often adults will be found clustered along the stems of a denuded Sweet Clover, Wild Licorice, or young Locust). They are sometimes abundant in open thickets of Sandbar Willow, and likely that is another favored food.

Overwintering as eggs, hatching in late spring or early summer, with adults in summer and autumn.

Often treated as a subspecies of M. foedus, but behaves as if a different species with different habitat preferences. The two are easily distinguished where they occur in the same areas. It is possible that there is some hybridization between them, but if this occurs it is probably on an insignificant scale, and I [David Ferguson; as of 2012] have seen no evidence of it.

Where formerly abundant (1970's and early 1980's) along stretches of the Rio Grande in central New Mexico, and along the Arkansas River in eastern Colorado and western Kansas, the species seems to be gone now, and it should be watched for in those areas to verify whether it still exists there. It is possible that a combination of human disturbances, drought, and heavy encroachment of Salt Cedar are among causes for it's apparent disappearance from these areas (??).