Crossidius testaceus

Crossidius testaceus can be distinguished from congeners by its testaceous (yellowish-brown to reddish-brown) coloration. The specific epithet refers to this characteristic color. It is generally less boldly patterned than related species such as C. coralinus, which exhibits striking red and black markings. Subspecies C. t. maculicollis is characterized by spotted pronotal markings.

Found in association with host plants in the Asteraceae family, particularly perennial shrubs such as Gutierrezia, Chrysothamnus/Ericameria, and Haplopappus. These host plants typically grow in arid and semi-arid western landscapes.

North America (western United States) and Central America. Specific records include Mexico and the United States.

Adults are active in late summer and early fall, coinciding with the blooming period of their host plants. Collection records indicate peak activity from August through September.

Adults feed on flowers of their Asteraceae host plants. Larvae bore through and feed on the roots of living, perennial shrubs.

• Ericameria nauseosa - host plantsubspecies ascendens of C. coralinus was found here; C. testaceus expected on similar hosts
• Gutierrezia - host plantgenus-level association for Crossidius spp.
• Chrysothamnus - host plantgenus-level association for Crossidius spp.
• Haplopappus - host plantgenus-level association for Crossidius spp.

Larvae develop in the roots of living host plants, a distinctive trait within Cerambycidae where most species develop in dead wood. Adults emerge in late summer, mate, and feed on host plant flowers. The complete life cycle spans multiple years.

Adults spend their brief adult lives perched on, feeding from, or mating upon host plant flowers. At night, they remain on the plants, burying themselves deeper among the flowers rather than seeking shelter elsewhere.

Larvae act as root borers in living shrubs, potentially influencing plant vigor and community composition in arid ecosystems. Adults may contribute to pollination of their host plants while feeding on floral resources.

Subject of entomological collecting and taxonomic study due to high geographic variation and polytopism within the genus. The species and its relatives are of interest for understanding speciation patterns in western North American insects.

• Crossidius coralinusLarger size and more boldly colored with bright red and black markings; C. testaceus is testaceous and less contrasting
• Crossidius pulchellusOccurs on similar host plants (Gutierrezia) but has distinct color pattern and distribution
• Crossidius suturalisSimilar size and host plant associations; distinguished by sutural markings and geographic range

• Cerambycidae
• long-horned beetle
• root borer
• Asteraceae
• western North America
• polytopic variation

• BugGuide
• Wikipedia
• GBIF taxonomy match
• iNaturalist taxon
• Catalogue of Life
• Halictidae | Beetles In The Bush
• Consolation Crossidius | Beetles In The Bush