The red milkweed beetle is a longhorn beetle that actually lives on and eats milkweed.
The bright coloration is a warning to would be predators, that just like the Monarch butterfly, the Milkweed longhorn beetle is poisonous.
Red Milkweed Beetle on bugguide.net.
Tetraopes tetrophthalmus on Wikipedia.
Red Milkweed Beetles.