Size: 8-9.4mm

Seasonality: Year-round, larvae generally emerge around the end of winter

Distribution; AK east to NS, ne. USA, MN, IA, CA, OR, WA, ID, MT, WY, the Archipelago of Azores, HI, across Europe.

Information:  extremely rare matte black morphs can be found, currently only one record which we have found, and the specimen was collected by Connor Graham in Keizer, Oregon.   Agonum muelleri prefer cooler temperatures and areas which are wet for most of the year, may be found amongst leaf litter along roadsides, in fields, lawns, gardens, forests, marshes, and in some areas, small river islands. Mostly nocturnal.

Description: body: elongate-ovate, slender, some individuals are elongate-quadrate, slender. Dorsal: head and pronotum shiny green, elytral brownish-bronze, antennae dark, antennal pubescence beginning on the second antennomere after the pedicel. Head smooth, no wrinkles nor ocular ridges. Pronotum rounded-quadrate, nearly square in some individuals; hind pronotal angles typically obtuse, with some individuals, close to a 90 degree angle. Pronotal disk impressed near hind angles, somewhat rough; rest of pronotum relatively smooth, with minor wrinkles ribbing out from the median line.  Pronotal margins thin, upturned, encircling the entirety of the disk. 7-8 shallow striae on each elytron, basal margins of pronotum do not overlap the base of the elytra>>scutellum exposed. Humeral angles rounded-obtuse, nearly right. Elytral lateral margins same width as pronotal lateral margins, also upturned. Ventral face dark iridescent green or iridescent black. Mature adults' legs are fully black, while the mature black morph A.muelleri has dark red femora and pale red tibiae.