Melanoplus devastator

Adults distinguished from similar Melanoplus sanguinipes (migratory grasshopper) by male genitalia: elongated slender cerci and long furculae extending halfway on supraanal plate (versus shorter cerci and furculae in M. sanguinipes). Both sexes share pale gray-tan body with black-spotted tegmina and pale greenish yellow venter. Nymphs separated from M. sanguinipes by lacking diagonal dark bar on compound eyes (present in M. sanguinipes) and by having larger ivory patches interrupting the dark stripe on hind femur medial area (smaller light patches in M. sanguinipes). Instar I nymphs are pale with clearly evident ivory crescent and pale yellow medial femur area with narrow dark stripe, versus dark with faint crescent and heavily fuscous-spotted femur in M. sanguinipes.

Medium-sized grasshopper with long wings extending beyond the abdomen. Body color is pale gray and tan with fuscous maculations; venter of abdomen is pale greenish yellow. Tegmen marked by a row of conspicuous black spots. Medial area of hind femur shows pale or reddish tan and fuscous patches. Hind tibiae usually blue but may be red (3% of males and 15% of females red at Jasper Ridge, California site). Male cerci elongated and slender; furculae long, extending halfway on supraanal plate. Nymphs pale yellow, pale tan, or pale green with ivory crescent on gena extending onto pronotum; hind femur with narrow dark stripe in center of medial area in early instars, interrupted by wide diagonal pale tan bar in later instars.

Inhabits semiarid rangelands dominated by forbs and annual grasses at elevations from near sea level to over 5,000 feet. Primary habitat is foothill rangeland in coastal states, particularly California's coastal and Sierra Nevada foothills. Preferred oviposition sites include well-drained hillocks, ridges, slopes, and banks of ravines with gravelly soil. Egg beds often concentrated near basal growth of forbs such as tarweeds and Russian thistle, among roots of filaree, or in small well-drained bare spots. Migrants invade valley agricultural lands including green pastures, orchards, vineyards, and crop fields.

Limited geographic range in far western North America. Main distribution in coastal states: primarily California (coastal and Sierra Nevada foothills), minor occurrence in Oregon and Washington. Not found in interior western states or Great Plains.

Hatching period ranges from 50 to 103 days, starting late April and extending to late July—unusually prolonged compared to sympatric species. Nymphal development extends through summer with some individuals still present in mid-October; nutritional stress appears to prolong development. Adults present from approximately July through fall. Reproduction delayed: females enter reproductive diapause during summer, with egg maturation triggered by decreasing day length beginning late September. Oviposition occurs in fall coinciding with autumn rains and renewed plant growth.

Polyphagous, consuming grasses, forbs, shrubs, and trees. Nymphs feed preferentially on legumes, filaree (Erodium spp.), and brome and barley grasses when green and succulent. When preferred plants mature and dry, late nymphs and adults survive on less palatable plants including needlegrass (Stipa spp.), tarweeds (Hemizonia spp.), and wild lettuce (Lactuca spp.), feeding on epidermis of stems and leaf edges. Grass seeds, whether naturally shed or dropped by harvester ants (Messor andrei) on their mounds, are favored food items. Adults feed on stubble and ground litter. Migrants observed feeding on grape, citrus, apple, pear, cherry, peach, apricot, prune, plum, almond, avocado, cabbage, tomato, beet, beans, marigold, alfalfa, clover, timothy, corn, and barley.

Univoltine with overwintering eggs. Eggs deposited in fall in pods 3/4 to 7/8 inch long, slightly curved, containing 20-31 pale yellow eggs 3.9-4.4 mm long. Embryonic development and hatching requirements not fully studied but prolonged hatching period suggests possible egg diapause or staggered development. Nymphs pass through six instars (both sexes), with development rate highly variable depending on nutrition and temperature; precocious individuals may reach adulthood in ~70 days. Unique among rangeland grasshoppers: females undergo reproductive diapause during summer, with oogenesis resuming in response to decreasing photoperiod in late September. Fall rains typically coincide with breaking of diapause, providing nutritious host plants for egg production.

Highly migratory when populations irrupt. Older nymphs form crawling bands that migrate downhill toward succulent vegetation, following ravines and drainages toward crops, often moving 5 miles or more. Adults are strong fliers; swarms may migrate 15 or more miles in a single day, with observed distances of at least 30 miles. Non-migratory adults when flushed fly 3-6 feet at heights of 4-12 inches in straight silent flight; crepitation (wing-snapping sound) rarely heard. Daily activity pattern: bask in morning sun for approximately two hours, feed during cooler morning and late afternoon periods, climb vegetation to escape ground temperatures exceeding 130°F during midday heat. Courtship behavior not specifically studied; presumed similar to congeners with male stridulation and mounting attempts.

Primary consumer in semiarid rangeland ecosystems. During outbreak phases, can become dominant member of grasshopper assemblages, coexisting with Oedaleonotus enigma, Camnula pellucida, Dissosteira pictipennis, and others. Population crashes associated with fungal disease (Entomophaga grylli), which can reduce populations by 90%. Migrants that invade valley agricultural habitats fail to establish breeding populations, reasons unknown.

Major agricultural pest in California, minor pest in Oregon and Washington. Historical records of destructive populations date to 1722 (Spanish settlement era). Severe outbreaks in 1855 affected California, Oregon, and Washington. Most recent general outbreak 1955-1961 with annual infestations of 580,000 to 4,523,000 acres; over 3 million acres infested in 1957, over 4.5 million in 1958. Damage includes destruction of rangeland forage, defoliation of orchards and vineyards, destruction of grain fields (barley, corn), vegetable crops, and gardens; bark of young fruit trees and grape vines gnawed and consumed, killing terminals. Post-1961 irruptions have remained below 500,000 acres annually. Control efforts historically significant; modern management integrated with broader grasshopper IPM programs.

• Melanoplus sanguinipesClosely related member of mexicanus group with which M. devastator was historically confused; genetic studies suggest possible conspecificity or subspecies relationship, but maintained as separate species based on structural, life history, and geographic differences. Distinguished by male cerci and furculae shape, nymphal eye markings, and hind femur pattern.
• Oedaleonotus enigmaCo-occurs in California rangeland assemblages and may dominate in valley and low foothill habitats where M. devastator is less successful; both species can contribute to outbreak damage but have different habitat preferences and seasonal cycles.
• Camnula pellucidaSympatric in California foothills, often co-dominant in outbreaks; C. pellucida dominates in montane grasslands while M. devastator dominates in lower elevation foothill rangelands. Differentiated by morphology (clear wings in C. pellucida) and life history.

• pest species
• agricultural pest
• migratory
• diapause
• California endemic
• outbreak species
• rangeland
• orchard pest

• BugGuide
• Wikipedia
• GBIF taxonomy match
• iNaturalist taxon
• NCBI Taxonomy
• Catalogue of Life
• Devastating Grasshopper
• List of Species Fact Sheets| Grasshoppers of Wyoming and the West
• Field Guide
• Differential Grasshopper
• Dawson Grasshopper
• Finned Grasshopper