Calathus opaculus

Ground Beetle
Calathus opaculus

Identification:

Ground Beetle Calathus opaculus. Photo 3 of 4 tasting sugar from plastic lid found in the meadow. January 01, 2011 temp 48 (9C). Wheatley, Ontario.
Ground Beetle Calathus opaculus. Photo 3 of 4 tasting sugar from plastic lid found in the meadow. January 01, 2011 temp 48 (9C). Wheatley, Ontario.

Head: Narrow, half as wide as thorax; reddish-brown to blackish, dull. Whiskers (palpi) yellowish-brown.
Antenna: Yellowish-brown, long, reaching to mid-wing. Segment 2 short.
Thorax (Pronotum): Reddish-brown to blackish, dull, smooth and squarish; almost as wide as wings (elytra). Faint indented line down middle. Side borders (rim) outlined in orange-reddish to yellowish-brown (same colour as antenna and legs), the colored border widening and extending inward along lower margin.
Wings (Elytra): Reddish-brown to blackish, dull. Wings widen somewhat along sides, then taper to blunt, squarish tip. Wings have a narrow orange-reddish to yellowish-brown outside border (rim). About 10 shallow grooves on each wing (striae).
Legs: Orange-reddish to yellowish-brown. Middle and hind legs very long, shins (tibiae) and feet (tarsi) of equal length; shins have rows of hairs.
Abdomen: Tip of abdomen squared.

Similar Species: Calathus gregarius is larger and has shiny elytra. The reddish-orange borders are narrower and do not extend across lower margin of thorax.

Size: 8  to 11 mm.

Habitat: Carolinian forests.

Food: Smaller insects.

Flight Time: January to November

Life Cycle: Nocturnal adults active year-round and hide under rocks and leaves during the day. Occasionally attracted to lights.

Comments: Essex County – Point Pelee National park. Kent County – Rondeau Provincial Park. Photographed in Wheatley Jan 01, 2011 – temperature 48 F.

For information on synonyms, references and type specimens see next page