Distribution. The redlegged grasshopper, Melanoplus femurrubrum (De Geer), is known from nearly all of the United States and southern Canada, and its distribution also extends south through most of Mexico. In parts of the southeast, on the coastal plain from eastern North Carolina to southern Mississippi and Louisiana, and including all of Florida, it is replaced by a very similar form, M. propinquus Scudder, which appears to be a separate species (Dakin, 1985). These are native insects.
Host Plants. These species are polyphagous, feeding on a broad range of plants and apparently preferring a dietary mixture over a single food plant, and broadleaf plants over grasses. The preferred habitat is tall vegetation in pastures, fence rows, along irrigation ditches and roadways, and in fallow agricultural fields which have become weedy. The redlegged grasshoppers are known throughout North America for damage to crops, attacking alfalfa, barley, birdsfoot trefoil, clover, corn, lespedeza, oat, orchardgrass, soybean, timothy, tobacco, and vetch in addition to vegetables. Among vegetable crops, bean, beet, cabbage, and potato seem to be most frequently injured, but nearly any crop may be fed upon. Among the uncultivated plants eaten are aster, Aster spp.; Kentucky blue-grass, Poa pratensis; brown knapweed, Centaurea jacea; cinquefoil, Potentilla argentea; dandelion, Taraxacum officinale; fleabane, Erigeron divergens; goldenrod, Soli-dago canadensis; kochia, Kochia scoparia; Russian thistle, Salsola kali; smooth brome, Bromus inermis; sweet clover, Melilotus officinalis; wavyleaf thistle, Cirsium undu-latum; western ragweed, Ambrosia psilostachya; and likely many others. The weeds fed upon most frequently in North Dakota alfalfa fields were reported to be kochia, Kochia scoparia, field bindweed, Convolvulus arvensis; awnless bromegrass, Bromis inermis; and foxtail, Setaria spp. (Mulkern et al., 1962). On prairie, redlegged grasshopper ate primarily Kentucky blue-grass, Poa pratensis; western ragweed, Ambrosia psilos-tachya; golden aster, Chrysopsis villosa; flixweed, Descurainia sophia; and leadplant, Amorpha canesens (Mulkern et al., 1964). Bailey and Mukerji (1976) were able to culture redlegged grasshopper on nearly all plants tested, though they completed development more rapidly when provided with plants on which they preferred to feed.
Natural Enemies. The natural enemies of the crop-feeding Melanoplus spp. are quite similar. For information on natural enemies of redlegged grasshopper, see the section on natural enemies of migratory grasshopper, Melanoplus sanguinipes (Fabricius).
Weather. Like most grasshoppers, redlegged grasshopper is favored by hot weather. Long-term periods of drought and hot weather favor population increase, especially in northern areas that normally are cooler. A certain amount of precipitation is necessary to provide adequate food for the grasshoppers, of course, but prolonged cool, wet weather, especially during the period of eggs hatch, is detrimental for survival. The late onset of winter can favor grasshopper population increase because it allows adults additional time to produce eggs.
Life Cycle and Description. There is only a single generation per year throughout the range of these species, with the egg stage overwintering. Eggs hatch in late spring and adults are present from July until they are killed by heavy frost, though their numbers decrease steadily throughout the season. The follow ing information has been derived from studies of M. femurrubrum, but likely applies equally well to M. propinquus.
The males, but not the females, of these two species are easily separated by the genitalia. In M. femurrubrum, the cerci are pointed at the tip, formed by an acute angle. The cerci at the mid-point are relatively broad, about one-half the maximum width at the base. The furcula in this species diverge from the base and then converge distally, the space between the arms of the furcula forms a "U" shape. In contrast, in M. propinquus the tips of the cerci are rounded, and the cerci are relatively narrow at the mid-point, about one-third the maximum width at the base. The furcula diverge more strongly, the space between the arms forms a "V" shape (Dakin, 1985).
Adults normally roost at night on the tops of tall grasses and weeds. Early in the morning they crawl down the plant and resume feeding when the air temperature warms, often moving along the soil in search of food. As happens with nymphs, the adults ascend vegetation to escape high temperature. In the evening, they perch again on elevated roosts, and remain there until they are warmed by sunlight in the morning. Females have a pre-oviposition period of 9-15 days before they commence egg laying. Redlegged grasshopper is a fairly strong flier and can fly 10 m if disturbed. (See color figure 163.)
Despite its importance, comprehensive treatment of M. femurrubrum biology is lacking. Some important aspects were given by Parker (1939), Shotwell (1941)
Male redlegged grasshopper, tip of abdomen.
and Bellinger and Pienkowski (1989). A very good synopsis was presented by Pfadt (1994d), who also pictured all stages of development. A summary of red-legged grasshopper biology, including keys to related Canadian Orthoptera, was given by Vickery and Kevan (1985). Melanoplus femurrubrum was included in many grasshopper keys, including those by Blatch-ley (1920), Dakin and Hays (1970), Helfer (1972), Capi-nera and Sechrist (1982), and Richman et al. (1993). Blatchley (1920) includes M. propinquus; and Dakin and Hays (1970) treated the two redlegged grasshoppers as subspecies. Melanoplus femurrubrum was also included in a key to grasshopper eggs by Onsager and Mulkern (1963). Rearing of Melanoplus spp. was described by Henry (1985).
Redlegged grasshopper is a defoliator, often removing all leaf tissue and leaving only plant stems. Lower densities leave plant ragged or tattered. Redlegged grasshopper is a common component of the grasshopper complex that affects plants growing along the margins of fields, though it causes extensive damage only during periods of very high density. Redlegged grasshopper is capable of developing high densities and migratory tendencies during periods of drought, and may be found mixed into swarms of migratory grasshopper, Melanoplus sanguinipes (Fabricius).
Management of the various Melanoplus spp. grasshoppers is substantially the same. For information on redlegged grasshopper management, see the section on management under migratory grasshopper, Melanoplus sanguinipes (Fabricius).
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