The Fake Milkweed Bug

Top Photo: Mystery bugs.

Just outside the doors leading from Play To Learn in the main building here at the museum, and on your right, is a small garden planted with native prairie plants. I stop here when I pass through Gateway Park to watch goldfinches pick the seeds from the various herbaceous plants in the garden. And, there’s a large pokeweed in the center of the garden which attracts fruit eating birds. Catbirds seem especially fond of poke berries.

Male American goldfinch picking seeds.

On this day, I noticed a couple of brightly colored insects on one of the sunflower seed-heads. Looking closer I realized there were many more. There were both nymphs and adults. I had to stop and think about what they were. They were familiar to me but I couldn’t recall exactly what species. The fact they were on sunflower gave a clue. Though they resembled milkweed bugs, they definitely weren’t. Milkweed bugs, both large milkweed bugs and small milkweed bugs eat milkweed seeds, not sunflower, though the small milkweed bug has been observed eating other seeds and even other insects.

Mystery bug nymphs and adult (top).
Two mystery bug adults.

There are a number of red and black, or orange and black plant bugs, but they all have different preferences in what they eat. There’s the boxelder bug, the elm seed bug, cotton stainer, the list goes on. And, as you can see, the name of the plant they’re associated with is often part of the name given them.

I knew what these orange and black bugs weren’t, I needed reminding of what they were. I only had to check my photo library for sunflower seed bugs to confirm. Simple, right?

The problem, I soon remembered, was this insect was not named after its food preference but its similarity to another look-a-like insect, the large milkweed bug, or perhaps the small milkweed bug, both orange and black bugs. I don’t see small milkweed bugs often here at the museum. However, large milkweed bugs are ubiquitous on milkweed in late summer and early fall (I don’t have photos of small milkweed bug).

Large milkweed bug on milkweed.

To the point, these insects are called false milkweed bugs. Besides their different preferences in food from the true milkweed bugs, the pattern on their backs and face is not the same (above and below).

It’s all coming back to me now. Though, I’ll probably have to refresh my memory should I come across the same bugs again next year.

False milkweed bug on sunflower leaf. Note two black “Vs” on back.

Next time you pass milkweed plants check the seed pods for large milkweed bug adults and nymphs.

Large milkweed bug nymphs with one adult (left) on common milkweed seed pod.

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