Trimerotropis pallidipennis

Distinguished from other Trimerotropis species by combination of: two transverse dark bands on tegmen crossing entire width; hindwing with narrow black band at center (not broad as in some congeners), white to pale yellow disk, and transparent apex; pronotal median carina incised twice with straight ventral edge lacking tooth; inner hind femur black with two yellow bars; yellow hind tibia. Nymphs identifiable by triangular foveolae, pronotal carina structure, and hindleg color pattern with black bars on pale tan ground in later instars.

Primary habitats are deserts and semideserts of western North America, characterized by shrubs, forbs, and grasses with preponderance of bare ground used for basking and resting. Also occurs in sagebrush habitats at higher elevations (to 1,746 ft in Colorado) and weedy urban lots. Requires bare soil for oviposition and basking.

Most widely distributed bandwinged grasshopper in the New World; ranges from southwestern Canada through western United States to Argentina. In North America, occurs from southern British Columbia and Alberta south through all western states to Mexico. Documented in Wyoming, Colorado, Utah, Arizona, New Mexico, California, Idaho, Nevada, and Texas. Accidentally introduced to Hawaii (Oahu) in 1966, where it persisted through 1968.

Hatching begins in late February in south-central Arizona, late April in Utah, and early June in Colorado and Wyoming. Adults appear mid-April in southern Arizona, early June in northern states. One generation per year in northern range; two or more generations possible in southern Arizona with favorable moisture. Second generation hatching in early June in south-central Arizona.

Polyphagous, feeding on variety of forbs and grasses with diet shifting based on availability and quality. Early spring diet dominated by annual grasses including downy brome (Bromus tectorum) and needle grama (Bouteloua aristidoides). Later switches to green perennial grasses and forbs when annuals desiccate. Documented food plants include: downy brome, crested wheatgrass, thickspike wheatgrass, Sandberg bluegrass, blue grama, milkvetch, western salsify, big sagebrush, hoary aster, Greene rabbitbrush, gray rabbitbrush, Cryptantha sp., Solarium sp., Iva sp., Allionia incarnata, and Franseria deltoidea. Laboratory preferences include dandelion, kochia, downy brome, crested wheatgrass, and needle-and-thread. Crop contents occasionally contain arthropod parts, fungi, and pollen.

Overwinters as eggs in soil pods at approximately 1 inch depth. Eggs enter diapause shortly after laying; development resumes with moisture and warmth. Under laboratory conditions (82-104°F), eggs hatch in 13-21 days without diapause. Nymphal period 31-60 days depending on temperature: 50 days at 70-84°F, 31-33 days at 81-101°F. Females have five or six instars, males usually five. Adults live 67-80+ days. Females lay curved pods 1 inch long, 1/8 inch diameter, averaging 34 eggs per pod; maximum recorded 27 pods and 955 eggs per female. Preoviposition period averages 43 days (minimum 26 days).

Diurnal activity with basking on bare ground. Strong flight capabilities with flushed individuals flying 2-3 feet high, often exceeding 100 feet. Extended flight documented: one male circled for 17 minutes, swarms reported at 3,000-5,000 feet altitude. Nocturnal swarming to artificial lights during outbreaks. Crepitation (snapping sounds from hindwings) by males during flight initiates pair formation. Courtship involves stridulation producing trilling sounds, with 1-8 trills in quick succession. Marked individuals have been recovered up to 27 feet per day average displacement; low recapture rates (25%) indicate substantial emigration by flight.

Herbivore in desert and semidesert ecosystems; population irruptions can substantially reduce plant biomass. Serves as prey for various vertebrate and invertebrate predators. Eggs and nymphs vulnerable to desiccation, making rainfall a critical population-limiting factor. Outbreak populations may compete with other herbivores for forage resources.

Significant agricultural pest during outbreaks. Historical damage in Arizona (1958, 1998), California, New Mexico, and Utah. Crops damaged include wheat, cotton, carrots, sugarbeets, barley, milo, corn, safflower, and grapes. Defoliation and head-cutting in small grains; seedling consumption to ground level in cotton, requiring replanting. Swarms attracted to city lights create traffic hazards from crushed grasshoppers on roads. Six outbreaks recorded in Arizona 1952-1980, typically one year duration (maximum two years). Managed with insecticides and cultural practices during outbreaks.

• Trimerotropis cyaneipennisShares bandwinged pattern but has blue or greenish hindwing disk rather than white to pale yellow
• Trimerotropis cinctaSimilar size and habitat but differs in pronotal carina structure and hindwing band width
• Xanthippus corallipesOccurs in similar habitats but has different hindwing coloration and pronotal structure; distinguished by coral-pink or yellow hindwing disk with different banding pattern
• Trachyrhachys kiowaPrevious species in subfamily sequence, smaller with different wing venation and banding pattern

• grasshopper
• pest
• desert
• bandwinged
• swarming
• agricultural pest
• western North America
• polyphagous
• strong flier
• light-attracted

• BugGuide
• Grasshoppers of Colorado
• Species Records and Accounts
• Grasshoppers of Colorado
• Grasshoppers of Colorado
• Pallidwinged Grasshopper
• Detailed External Anatomy