Chestnut Herbal School

Large Milkweed Seed Bugs

Large milkweed seed bug, Oncopeltus fasciatus

I recently photographed some colorful milkweed bugs in my garden and decided to repost a small piece I had previously posted about these gorgeous gregarious insects with the new photos, figuring most of you didn't read the original essay, and would absolutely love to learn more about these charismatic insects. The large milkweed bug, Oncopeltus fasciatus, is a common inhabitant of the milkweed patch. These insects concentrate cardiac glycosides in their tissues, similar to monarch caterpillars and butterflies, and advertise their toxicity with bright red and black coloration. The large milkweed bug feeds collectively on the immature milkweed seeds while they are still in the pods. With their sucking mouthparts, they inject enzymes into the developing seeds, which liquefies and predigests the contents until it is ready to slurp up.

Oncopeltus-fasciatus-late instar cluster (immature milkweed seed bugs)

Interestingly, this species is so easy to rear in the lab, that it is the insect equivalent to the lab rat, with countless experiments being performed throughout the land. I even found a scholarly article on milkweed bug husbandry!

Butterflyweed -Asclepias tubersoa seeds, note the wee milkweed seed bugs hiding in the pod

Butterflyweed flowerAsclepias tuberosa

large milweed bug with an immature instar on butterflyweed

Large milkweed bugs in love, wearing pollinia

Notice the yellow do-dads hanging off the feet of these lovebird milkweed bugs. These are masses of pollen, called pollinia. Pollinia are produced in lieu of loose pollen in certain plant families, such as the Orchid (Orchidaceae) and Apocynaceae (Dogbane and Milkweed family). These plants put all their eggs in one basket, by massing copious amounts of pollen in one masse, the pollinium.

Common milkweed, Asclepias syriaca

Honk if you love large milkweed seed bugs!

One thought on “Large Milkweed Seed Bugs

  1. Beautiful glitterati of the bug world! And those babies are as cute as bedbugs! They remind me of my little guy when he was a wee wiggly worm, dressed in his halloween onesy. A little racy though showing bug coitus with those pollinia still on their feet – OOOH LA LA!!!!

    Thanks, Juliet for teaching me what these ubiquitous buggers are – now I can sound like i know what I’m talkin about in the garden!

    And those other photos were fantabulous!


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