The Cerambycidae, or long-horned beetles, get their common name from their antennae. Characteristic of this family is the antennae are inserted in close proximity to the eyes, so that most have an indentation of the eye. Tetraopes carries this to the extreme, so that the antennae actually split each eye in two, hence its name.

Tetraopes is one of the few insects that can safely feed on milkweed. (Asclepias spp.) Others include the Monarch butterfly caterpillar and the milkweed leaf beetle, Labidomera clivicollis.

This is a male specimen. Males are slightly smaller than females.

"Plant chemical defenses can be eaten by herbivores, stored, and used in defense against predators. To be effective defensive agents, the sequestered chemicals cannot be metabolized into inactive products. Utilizing plant chemicals can be costly to herbivores because it often requires specialized handling, storage, and modification (Bowers 1992). This cost can be seen when plants that utilize plant chemicals are compared to those plants that do not in a situation where herbivores are excluded.

Caterpillar and adult monarch butterflies store cardiac glycosides from milkweed, making these organisms distasteful. After eating a monarch caterpillar or butterfly, its bird predator will vomit and will avoid eating similar individuals in the future (Huheey 1984).
Species that feed on milkweeds are usually aposematically colored. Aposomatic species are those that “advertise” their distastefulness by being brightly colored (see Guilford 1990). Two different species of milkweed bug in the family Hemiptera, Lygaeus kalmii and Oncopeltus fasciatus, are thus colored, with bright orange and black markings." From Wikipedia "Herbivore adaptations to plant defense."