Triepeolus concavus (Cresson, 1878)
Length ca. 10–16 mm; ITW 2.2–3.1 mm. Integument entirely black or dark brown, except often ferruginous apically on mandibles, basolaterally on labrum, and laterally on F1; dorsum of mesosoma and metasoma with bands of yellow setae. Clypeus with weak midline and distinct larger punctures (partially obscured in specimens with brown/black setae on clypeus, especially males). Paramedian band indistinct from dense yellow setae covering anterior third to fourth of mesoscutum. Scutellum strongly to moderately bigibbous; axillar spine triangular, reaching midpoint of scutellum. Mesepisternum lacking erect, simple setae; with distinct region of yellow, branched setae on dorsal third to fourth; remainder black, covered with minute, contiguous punctures and black or dark brown, branched setae. T1 discal patch strongly rectangular to subovate (very reduced in some specimens from Arizona); T2 completely covered with pale yellow setae except for semicircular to trapezoidal basal black region. Female: Pseudopygidial area with long, stout setae forming posterior “plate”; S5 strongly downcurved; ventral meso- and metasomata entirely dark brown. Male: Pygidial plate relatively wide, with distinct basal transverse ridge; metasomal sterna with setae dark brown except sometimes with white setae laterally on S3; S3 with apical setae slightly surpassing apical margin; S4–S5 with dark brown apical fringes.
Ecology and Distribution
Helenium sp., Helianthus annuus L., H. tuberosus L., Heliopsis helianthoides (L.) Sweet, Lepandena marginata (= Euphorbia marginata Pursh), Prionopsis ciliata (= Grindelia papposa Nesom & Suh), Ratibida pinnata (Vent.) Barnh., Verbesina sp., Vernonia baldwinii Torr., “star thistle” (= Centaurea).
USA: Alabama, Arizona, Arkansas, California (the Central Valley, and extending further south into San Bernardino Co. and Riverside Co.), Colorado, Florida, Georgia, Idaho, Illinois, Indiana, Kansas, Louisiana, Michigan, Minnesota, Mississippi, Missouri, New Mexico, North Carolina, Oklahoma, Texas, Utah, Washington, Washington D.C., Wisconsin.