C1. Lubber grasshoppers (Romaleidae)
Our largest grasshopper is a member of this family. These species are characterized by possessing apical spines on both the mesal and lateral face of the hind tibiae and in having the two basal lobes of the hind femur subequal (dorsal lobe is larger in Acrididae). Winged members of this family have a specialized stridulatory mechanism in which some cross-veins of the hindwings have serrations that are scraped across a keeled forewing longitudinal vein. Only one species, Brachystola magna occurs in the Dakotas. A second species, Romalea guttata is widely used in biology classes. Both are included in the key to illustrate the diversity within the Romaleidae.
A. Wing length < pronotum, lateral carinae present, posterior lobe of pronotum evenly rounded, prosternal tubercle absent.
B. Wing length > pronotum, lateral carinae weak, posterior lobe of pronotum forming an angle of 90o, prosternal tubercle present.
Romalea guttata
C2. Bird locusts (Acrididae: Cyrtacanthacridinae).
Often grouped with the Melanoplinae, the bird locusts or Cyrtacanthacridinae differ principally (from all other American Acrididae) in that the mesosternal lobes are longer than wide. Additional characters include the ‘u’- shaped subanal plate, the antennae being more than ½ the body length, the vertically rather than horizontally stripped eyes apparent in live specimens, and the nymphs with an arching acutely angled pronotum, resembling that of the Oedipodinae. Many Old World species have brightly banded hindwings.
This is an Old World group with a few members in the New World. The majority of species occur in Africa. Two species have been recorded from the Dakotas.
A. Cercus of male narrowing from base, truncate at apex; of female upturned, narrowing to rounded apex; tegmina blotched.
Schistocerca americana
B. Cercus of male about as wide at base as apex, widest sub-basally, apex weakly excavate with a dorsal and ventral lobe; of female nearly quadrate to triangular, blunt apex often very weakly bilobed; tegmina unmarked, pronotum with a pale median stripe.
C3. Spurthroats (Acrididae: Melanoplinae).
Characters used in the identification of spur-throated grasshoppers are: shape of the male cercus, color of the hind tibia, color and banding pattern on the femur, and wing length. The keys are primarily set up to work with males. Females are best told by association with males but can usually be identified once the male of that species is recognized. With practice females can be identified by cercus shape and color pattern. Two species of Slant-faced grasshoppers which have a rudimentary spur between the forelegs can be confused with members of the present group. In these species, the face is extremely slanted. Also see Bird-locusts.
North American melanoplines are closely related to
the African Calopteninae, the two groups have in the past been treated as a single subfamily. In the synopsis that
follows, the Melanoplinae are divided into 10 groups for identification purposes.
Only group '6' is a taxonomically valid entity.
Length when used within these groups is a measurement excluding the wings.
C4. Slantfaced hoppers.
In addition to the characters listed previously, these hoppers often have the antennae either flattened near the base– sword shaped (ensiform) or clubbed (capitate). The arolium when largest is usually rounded rather than egg-shaped– one exception with weakly clubbed antennae, clear wings and no throat spur. There are two slant faced species with a rudimentary prosternal spur, and an additional species with colored hindwings and strongly angulate pronotum– all are markedly slant faced with modified antennae.
On a world basis, this appears to be an artificial group (paraphyletic) with species belonging to the band-wings, others as outliers of groups common in Eurasia or Africa. Some authors merge this and the following group. Our species (Gomphocerinae) are here placed into nine groups for identification:
C5. Bandwings (Acrididae: Oedipodinae)
Many members of this subfamily have the hindwings yellow or red and edged with black. Others have black hindwings with pale edges, and a few species (including the most economically important ones) have clear hindwings.
In this group, the arolium is extremely small or absent. Most species have a triangular to oval shaped depressed area (fastigum) on the dorso-anterior portion of the head above the eyes. Immediately above each eye is a variously shaped depression, the foveola. In addition, a ridge can be traced near the leading edge of each tegmen. This ridge marks the intercallary vein which, in most species, is rubbed by the hind femur to produce sound. One slant-faced hopper has both the pronotal characters and colored wings of this group, and is also included here.
Groups of Bandwings are separated for identification purposes by the number of sulci crossing the median carina of the pronotum, wing patterns and hind tibial colors. The eight groups are:
C6. Pygmy grasshoppers (Family Tettigidae).
These small hoppers are cosmopolitan in distribution, the majority of species occurring in Southeast Asia. All possess an elongated pronotum which extends over the abdomen. Also called Grouse locusts, they feed on mosses, algae, and possibly detritus.
A. Antennae with > 20 segments, pro-femur with two carinae.
Tettigidea lateralis
B. Antennae with < 16 segemts, pro-femur with a single median carina.
a. Antennae of 12 or 13 segments. Pronotum arched, with tegminal sinus much smaller than lower sinus.
Nomotettix cristatus
a.’ Antennae of 14 to 16 segments. Pronotum may be arched anteriad, tegminal sinus and lower sinus subequal in size.
b. Fastigum not projecting forward beyond eyes in dorsal view, fastigum narrower than one eye-width.
Paratettix cucullatus
b.’ Fastigum projecting forward beyond eyes in dorsal view, fastigum slightly wider than one eye-width.
c. In dorsal view, fastigum angulate with median carina not projecting.
d. In profile, face nearly straight from antennal base to vertex.
Tetrix subulata
d.’ In profile, face emarginate between antennal base and vertex.
Tetrix brunneri
c.’ In dorsal view, fastigum truncate or convex with median carina projecting.
d. In profile, face weakly emarginate from antennal base to vertex, pronotum with median carina evenly convex to evenly and shallowly concave over abdomen.
Tetrix ornata
d.’ Face strongly emarginate from antennal base to vertex, median carina with a strong and weak convexity over thorax.
Tetrix arenosa
C7. Pigmy mole-crickets (Tridactylidae)
Of the approximately 80 species of pigmy mole-crickets world-wide, 36 occur in the New World and two occur in the Northern Great Plains. Tridactylids inhabit moist or sandy areas, often along stream banks where they form aggregations of mud burrows. They feed on minute plant materials.
A. Hind tarsus > length of apical tibial spurs, prosternum with a median process. Color uniform brown or blackish.
Neotridactylus apicialis
B. Hind tarsus < ½ length of apical tibial spurs, prosternum without median process. Patterned in black and yellow.
Ellipes minutus