Therion nigripes

Therion species are medium-sized ichneumonids with characteristic wing venation including a distinct areolet in the forewing. Therion nigripes can be distinguished from congeners by its black legs (reflected in the specific epithet), contrasting with species that have pale or partly pale legs. The body is generally robust with a moderately long ovipositor. Precise identification requires examination of detailed morphological characters including propodeal sculpture and antennae proportions, ideally through comparison with type material or expert determination.

The species has been documented in North America. Specific locality records are sparse due to limited collection effort. The genus Therion has a primarily Holarctic distribution, with most North American species occurring in forested regions.

As a member of the genus Therion, this species likely functions as a koinobiont parasitoid of caterpillars, contributing to natural regulation of lepidopteran populations. This ecological role is inferred from documented biology of congeneric species, though direct observations for T. nigripes are lacking.

• Therion circumflexumOverlapping distribution and similar body form; distinguished by leg coloration (T. circumflexum has partly pale legs) and subtle differences in wing venation and propodeal structure.
• Therion morioSimilar size and general appearance; T. morio typically shows different color patterns on the mesosoma and lacks the uniformly black legs characteristic of T. nigripes.

• BugGuide
• GBIF taxonomy match
• iNaturalist taxon
• Catalogue of Life