Prionus integer

Distinguished from other Prionus species by combination of: occurrence in shortgrass prairie habitat (not oak woodland), simple filiform antennae in females versus flabellate in males, and lack of the highly segmented antennae (30+ segments) characteristic of P. fissicornis in subgenus Antennalia. Males attracted to prionic acid lures shared with other Homaesthesis species. Burrowing behavior in adults—creating shallow soil burrows—is apparently unique among documented Prionus species and serves as a behavioral indicator.

Shortgrass prairie in semi-arid regions. Specifically documented from dry grasslands with sandy/loam soils in southeastern Colorado. Adults found along roadsides where vegetation is lusher due to rain shedding by the road. Burrows occur in soil exposures, often at the base of small bunch grasses. Absent from oak woodland or pinyon-juniper habitats where related species like P. heroicus occur.

Endemic to the United States. Documented from shortgrass prairie of southeastern Colorado (Bent County, north of Las Animas) and potentially other Great Plains localities with similar habitat. GBIF records indicate presence in US. Precise range boundaries unknown due to limited collecting effort and recent discovery of effective survey methods.

Adults active in June. Emergence appears triggered by rainfall events; documented emergence following heavy afternoon/evening rain with peak activity at dusk. Morning searches have found inactive individuals in burrows. Seasonal activity likely corresponds to summer rainy period in semi-arid grasslands.

Larvae have been associated with roots of sagebrush (Artemisia tridentata) and yellow rabbitbrush (Chrysothamnus viscidiflorus). Two records document larvae damaging newly planted beans and cutting underground stems of potato plants in southern Idaho, apparently in fields recently cleared from native rangeland. Adults do not feed; mouthparts not adapted for feeding.

• Artemisia tridentata - larval food plantbig sagebrush; roots consumed by larvae
• Chrysothamnus viscidiflorus - larval food plantyellow rabbitbrush; roots consumed by larvae
• Phaseolus vulgaris - larval food plantbeans; larvae damaged newly planted fields in Idaho where native vegetation had been cleared
• Solanum tuberosum - larval food plantpotato; larvae cut underground stems in Idaho fields

Complete metamorphosis with subterranean larval stage. Larvae feed on roots of host plants. Pupation occurs in soil. Adults emerge following rainfall events, with mass emergences documented. Adults are short-lived and do not feed. Females excavate shallow burrows in soil, possibly for pheromone emission or mating rendezvous; function of burrowing behavior remains unclear. Oviposition presumably occurs into soil at base of plants, though direct observation of egg-laying not confirmed.

Adults of both sexes create shallow soil burrows approximately two inches deep, with fresh diggings visible at the surface. Burrows are often located at the base of bunch grasses. Females have been observed sitting within burrows with rhythmic abdominal movements, possibly associated with pheromone emission. Males are strongly attracted to prionic acid lures and fly upwind to locate females. Mass emergences occur following rainfall, with hundreds of individuals appearing within hours. Mating occurs on the surface; males attempt to mate with females near burrow entrances. Adults are flight-capable but often crawl actively on ground and vegetation.

Larvae function as root herbivores in shortgrass prairie ecosystems, potentially contributing to nutrient cycling and plant community dynamics. Larval feeding on woody shrub roots (sagebrush, rabbitbrush) suggests role in semi-arid shrubland/grassland ecotones. Mass emergence events provide concentrated food resource for predators. Specific predators undocumented, but likely preyed upon by birds, mammals, and other insects.

Minor agricultural pest in Idaho, where larvae have damaged bean and potato plantings in fields converted from native rangeland. Not considered a significant economic pest compared to congeners P. laticollis (eastern orchards) and P. californicus (western orchards). Of interest to entomologists and collectors due to recent development of effective pheromone-based survey methods using prionic acid lures.

• Prionus fissicornisAlso occurs in Great Plains shortgrass prairie and attracted to prionic acid lures. Distinguished by highly segmented antennae (30+ segments) in subgenus Antennalia versus P. integer in subgenus Homaesthesis; P. fissicornis adults do not create burrows.
• Prionus heroicusLarge species with similar robust build, but occurs in oak/pine/juniper woodland habitats of southwestern US, not shortgrass prairie; males also attracted to prionic acid but species distinguished by habitat and distribution.
• Prionus emarginatusAnother Homaesthesis species from Great Plains grasslands; specific distinguishing features not detailed in available sources but likely separable by subtle morphological differences and allopatric or parapatric distribution.

• Cerambycidae
• Prioninae
• longhorned beetle
• Great Plains
• shortgrass prairie
• pheromone attraction
• burrowing behavior
• root feeder

• BugGuide
• Wikipedia
• GBIF taxonomy match
• iNaturalist taxon
• Catalogue of Life
• How to catch “bucket loads” of Prionus fissicornis! | Beetles In The Bush
• My first experience with Prionus lure | Beetles In The Bush
• 2014 Great Plains Collecting Trip iReport | Beetles In The Bush
• November | 2014 | Beetles In The Bush