any of a group of insects in the true bug order, Heteroptera, that includes many important crop pests. There are between 3,000 and 5,000 species of lygaeid bugs, which vary from brown to brightly patterned with red, white, or black spots and bands. The large milkweed bug (Oncopeltus fasciatus) is distinguished by its broad red and black bands. They range from 3 to 15 mm (0.1 to 0.6 inch) in length, although they are usually less than 10 mm.