On Milkweed

Longhorn milkweed beetles mating on milkweed, Frick Park, 2 July 2024 (photo by Charity Kheshgi)

12 July 2024

Last week Charity Kheshgi and I found bugs mating on milkweed that I had never noticed before.

The red milkweed beetle (Tetraopes tetrophthalmus) is one of 14-17 species of longhorn milkweed beetles in U.S. and Canada. They are host-specific on common milkweed (Asclepias syriaca). The females are even eating while mating.

Though they eat the plant they don’t like getting stuck in milkweed sap so they limit their exposure to it by purposely draining the veins.

(video of a red milkweed beetle cutting milkweed vein to reduce/stop latex pressure before feeding beyond the cut, embedded from Wikimedia Commons)


Other expected milkweed insects have not made an appearance yet. I have seen neither large nor small milkweed bugs. I usually find them on milkweed pods but the plants are only in the leaf growth and flowering stage right now.

Large and small milkweed bugs (photos by Kate St. John and John English)

Meanwhile, friends who grow milkweed to attract monarch butterflies are concerned that they have not seen any monarchs yet. Was last week too early? Steve Gosser photographed this one in July 2014.

Monarch butterfly on swamp milkweed, July 2014 (photo by Steve Gosser)

Have you seen monarch butterflies this month in southwestern PA?

If so, leave a comment to let me know.

4 thoughts on “On Milkweed

  1. Kate I haven’t seen any Monarchs just one that was black and yellow. I am missing the butterflies this year.

  2. Hi Kate,

    To answer your question, yes. I just released a female Monarch the other day. And I have a caterpillar that will be ready to “J” here likely over the weekend or early next week.

    But also it is true I am not seeing the numbers like I use to. I remember one year I had Monarchs egg laying in early May. I have not seen that in some time.

  3. No monarchs yet. I never see them until migration in August. But even then, they are now scarce and don’t lay eggs on my milkweed anymore. Too many beetles? Or predators? Years ago I have seen a kind of large black wasp hunting and eating larvae off my milkweed. The wasps are still around, not the monarchs. Sadly.

  4. My sister in the West End Sheriden section of the city grows a bunch of milkweed for the butterflies. She found her first Monarch caterpillar last week and brought it inside to safely develop.

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