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Sunday, July 19, 2015

Red Milkweed Beetle

The red milkweed beetle, Tetraopes tetrophthalmus
The red milkweed beetle is another nice summer insect. It's a longhorned beetle, in the family Cerambycidae. Check out its extreme antennae.

The red milkweed beetle's genus and species names are derived from Latin and mean four-eyed. Many species in the longhorned beetle family have antennae that originate close to the eyes, some so close that the eyes look indented. In the red milkweed beetle each compound eye is completely separated into two by the placement of the antennae and violà -- four eyes!

Click to enlarge and check out the antenna with an eye on each side. 
Red milkweed beetles are among the few things that can eat the toxin-containing plants of the milkweed genus, Asclepias. They are able to store the toxins and end up unpalatable to potential predators, which they advertise with their showy colors.
Red milkweed beetles are not the only red and black insects you can find on milkweeds. I've written about two others: large and small milkweed bugs. The red X on its back identifies this small milkweed bug, Lygaeus kalmii

The ones with a broad black band across the back are called large milkweed bugs, Oncopeltus fasciatus. You can read a blog I wrote previously about these bugs by clicking here.  And another blog about both kinds by clicking here. 

Combined with monarch butterflies, that are also milkweed specialists in the caterpillar stage, red milkweed beetles and large and small milkweed bugs make for exciting times in the milkweed patch for insect enthusiasts.


  1. I love Milkweed and its many insect visitors. I read an interesting fact about the Red Milkweed Beetle, which feeds exclusively on the leaves of milkweed. The sticky latex of the sap would eventually glue the insect's mouth shut, except that it opens a vein upstream from where it is feeding, in order to stem the flow of sap. Isn't nature amazing?

    1. That's great, Jacqueline. I am a big fan of the milkweeds, too. I can spend a long time in a patch. :-)