Melanoplus rugglesi

Gurney, 1949

Nevada Sage Grasshopper

Melanoplus rugglesi is a medium-sized spur-throated grasshopper to the cold desert shrublands of the western United States. The exhibits pronounced phase , with solitary and migratory forms differing in body size, wing length, and coloration. Named in honor of entomologist Arthur G. Ruggles, this is notable for its extreme migratory and extended dynamics, with persisting at high densities for multiple years.

Pronunciation

How to pronounce Melanoplus rugglesi: /mɛˈlænoʊpləs ˈrʌɡlɛsi/

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Identification

Distinguished from the closely related Melanoplus occidentalis by male genitalia: M. rugglesi has a larger, quadrate and corkscrew-twisted lateral aedeagal appendage, whereas M. occidentalis has a slightly smaller, triangular cercus with evenly rounded apex and straight (needle-shaped) lateral aedeagal appendage. Nymphs identifiable by white genal crescent, pattern with diagonal dark bar, and hind color pattern with three alternating bars.

Appearance

Medium-sized with bright coloration. Inner and lower areas of hind bright orange; upper marginal and medial areas tan with three transverse dark bars, the middle bar of medial area usually chevron-shaped. Hind tibia blue. Wings long, extending 1–7 mm beyond apex of hind femur. Migratory phase individuals larger with brighter orange coloration; solitary phase individuals smaller with grayish rather than bright orange markings on pronotum and hind femur.

Habitat

Cold desert shrublands of the far West, dominated by sagebrush and associated shrubs with subdominant forbs and grasses in the understory. Preferred include areas with big sagebrush, black sagebrush, Douglas rabbitbrush, spiny hopsage, and shadscale.

Distribution

Mainly Nevada and Utah; also occurs in adjacent states including Oregon, Idaho, and British Columbia, Canada. Recorded from Glacier in Montana, presumably from long-distance .

Seasonality

Early-hatching . Hatching begins as early as April 1 in warm years, typically mid-April, continuing for 2–3 weeks. appear from mid-May to mid-June. Oviposition occurs from June through July. One per year with .

Diet

Primarily a shrub feeder, with five preferred shrubs: big sagebrush (Artemisia tridentata), black sagebrush (A. nova), Douglas rabbitbrush (Chrysothamnus viscidiflorus), spiny hopsage (Grayia spinosa), and shadscale (Atriplex confertifolia). Also feeds on downy brome (Bromus tectorum), scarlet globemallow, and other forbs and grasses. Laboratory studies indicate preference for young wheat leaves, dandelion, downy brome, and white sage.

Host Associations

Artemisia tridentata - food plantpreferred shrub
Artemisia nova - food plantpreferred shrub
Chrysothamnus viscidiflorus - food plantpreferred shrub
Grayia spinosa - food plantpreferred shrub
Atriplex confertifolia - food plantpreferred shrub
Bromus tectorum - food plantimportant nymphal

Life Cycle

with . Embryonic development occurs primarily in summer following oviposition, with breaking during winter. Five nymphal instars; development to adulthood requires approximately 6 weeks under field conditions, or 23 days at constant 90°F in laboratory. Preoviposition period approximately 21 days. Females produce 14–25 eggs per pod; pods 1–1.75 inches long. Long-lived females may produce up to 20 pods.

Behavior

Highly migratory in dense . migrate 2–4 miles daily, up to 40–75 miles per season, primarily in northerly direction. Swarm occur at heights of a few hundred feet, with updrafts lifting grasshoppers to several thousand feet. Nymphs of instars IV–V migrate as coherent bands, traveling up to 200 yards per day. spending most time on ground; basks by flanking (turning side perpendicular to sun, lowering hindleg). Ovipositing females highly gregarious, often more than 100 depositing simultaneously in small areas.

Ecological Role

Significant herbivore in cold desert shrub . During , defoliates, barks, and kills shrubs, disrupting plant biodiversity and promoting soil erosion and weed invasion. Serves as prey for various vertebrate and . Migratory may reduce local predator and buildup.

Human Relevance

Serious agricultural and rangeland pest during . The 1938–1951 Nevada outbreak and 1989–1996 Utah outbreak caused extensive damage to sagebrush, reducing winter forage for livestock and wildlife. Swarms destroyed garden crops including corn, lettuce, onions, radishes, beets, and potatoes. Minor damage to alfalfa and sweet clover. Despite control efforts, persisted for years due to into new .

Similar Taxa

Melanoplus occidentalisClosely related with similar general appearance; distinguished by male shape (triangular vs. quadrate) and straight vs. corkscrew-twisted aedeagal appendage
Melanoplus sanguinipesAnother highly migratory Melanoplus with phase ; differs in preference (grasslands vs. desert shrublands) and plant associations

More Details

Phase Polyphenism

Gurney (1949) recognized solitary and migratory phases differing in body size, wing length, and color intensity. Migratory individuals have larger bodies, longer wings, and brighter orange coloration; solitary individuals are smaller with grayish markings.

Outbreak Dynamics

persist for exceptionally long periods: 14 years in Nevada (1938–1951) and 7 years in western Utah (1989–1996). into new appears to safeguard from and buildup that typically collapse outbreaks of other .

Long-Distance Dispersal

Specimens recorded on Glacier in Montana in 1949, approximately 600 miles from the nearest known in southwestern Oregon, demonstrate potential for extreme long-distance transport by upper-level winds.