Large Milkweed Bugs (Oncopeltus fasciatus) feed on the seed pods of the various members of the Milkweed Family (Asclepiadaceae). These Large Milkweed Bugs are feeding on the seed pods of a Fringed Twinevine (Funastrum cynanchoides) along with a number of yellow aphids.

Large Milkweed Bugs accumulate the poisonous cardiac glycosides found in milkweed plants, and they themselves become quite poisonous. Their bold, orange and black coloration makes them quite visible and is meant as a warning to potential predators (especially birds with their generally good color vision) that they are poisonous.

Large Milkweed Bugs have a solid black bar across the middle of their topsides, while the similar Small Milkweed Bugs (Lygaeus kalmii) have an orange "X" across their topsides.