The large milkweed bug (Oncopeltus fasciatus) is colored orange-red and black. It has a long a long, thin tube that forms part of the mouth which is named proboscis. With that it pierces into plants and sucks their sap. As the name says, it feeds on the seeds, leaves and stems of milkweed. Milkeweed bugs are found in small groups. This behavior is likely meant to enhance their warning coloration.
Because this species feeds on milkweed it is fairly safe from predators. This is similar to the Monarch butterfly, whose larvae also feed on milkweed. Certain chemicals in the milkweed sap, called cardiac glycosides, are toxic which makes the adult safe from most predators. Interestingly the chemicals are not toxic to the milkweed bugs but they have the ability to store them. In order to warn potential predators the bugs wear this warning orange color.