This insect is a problem only if you're trying to grow milkweed.
The home gardener has nothing to worry about with this fair bug. The large milkweed bug (Oncopeltus fasciatus) lives almost exclusively on milkweed, piercing the plant's pods to feed on the seeds. The bugs often gather in groups on the underside of milkweed leaves.
The milkweed bug doesn't have any natural enemies. Because it concentrates the unsavory sap of milkweed in its body, it doesn't taste good to birds or other critters that might want to sample it. Its bright coloration reminds birds that it's a morsel best left alone.
The large milkweed bug is common throughout many parts of the United States. Thanks to this critter, the population of milkweed is kept in check.