Harpalus pensylvanicus is a species of ground beetle in the subfamily Harpalinae.

[1] The adults of the species are shiny black on the top, reddish brown underneath, and the elytra have lines.

The larvae are black with a reddish head and the body is tapered with two long cerci.

The species' food includes the seeds of ragweed and assorted grasses.

[2] They favor high hayfields opposed to low maize fields.