Red Milkweed Beetle

3 06 2012

Just a few facts that I’ve learned about the Red Milkweed Beetle (Tetraopes tetraophthalmus):

They are part of the Cerambycidae family—Longhorn Beetles.

Tetraopes, just like longhorned beetles, have antennae inserted in close proximity to their eyes, which is how they get their common name, “longhorned.” In the case of Tetraopes, it is more extreme so that the antennae actually split each eye into two (ouch!). So this little beetle actually has four eyes!

Butterfly fans know that the Monarch butterfly caterpillar feeds on milkweed (as well as the milkweed leaf beetle), but Tetraopes are one of the few insects that can safely feed on milkweed.

Males Red Milkweed Beetles are slightly smaller than females.

From The milkweed beetle, a herbivore, is given this name because they are generally host specific to milkweed plants (genus Asclepias). It is thought the beetle and its early instars (developmental stage) derive a measure of protection from predators by incorporating toxins from the plant into their bodies, thereby becoming distasteful, much as the Monarch butterfly and its larvae do. The red and black coloring are aposematic (from apo—away and sematic—sign/meaning, which is a warning coloration), advertising the beetles’ inedibility. There are many milkweed-eating species of insect that use the toxins contained in the plant as a chemical defense.

Who knew?! Order Coleoptera: Beetles are the dominant form of life on earth—one of every five living species is a beetle! Coleoptera is the largest order in the animal kingdom, containing a third of all insect species. There are about 300,000 known species worldwide, 30,000 of which live in North America.


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