any of some 750 species of insects (order Heteroptera) that burrow underground around clumps of grass, in sandy places, or beneath ground litter. These insects may be up to 7 mm (0.3 inch) long. Their oval bodies are brown or black, and there are spines on the tibia (part of the upper leg).

Sometimes the subfamily Thyreocorinae is elevated to the family level (Thyreocoridae). Its members, slightly smaller than those of the burrower-bug subfamily Cydninae, at one time were commonly called negro bugs but are now called thyreocorids. They are found on vegetation, flowers, and fruits, especially raspberries. These are usually shiny black in colour, but some are tinged with green or blue. They emit a disagreeable odour if handled. Thyreocoris pulicarius, a celery pest, is 3 mm long and has white stripes on each side of its body.