Crab spiders and ambush bugs
Misumena, Phymata
A flower that gathers this many insects also gathers the things that eat them.
What it does on milkweed
Crab spiders hold position in a flower head with their front legs spread, and some can shift color between white and yellow over several days to match where they are sitting. Ambush bugs do the same job with raptorial forelegs and take prey many times their own size. Neither builds a web. Both are part of why an umbel is worth watching for ten minutes.
How to recognize it
Crab spiders sit with the first two pairs of legs held wide, crab-fashion, usually white or yellow. Ambush bugs are small, angular, mottled yellow-brown and green, with thickened front legs.
Where and when
Throughout the United States. Most often seen June to September.
Should you do anything about it?
Leave them. A garden that supports predators is working, and their effect on monarch numbers is small next to habitat loss.
Crab spiders and ambush bugs: common questions
Do spiders eat monarch caterpillars?
Some do, along with wasps, ants, stink bugs and tachinid flies. Predation on eggs and small larvae is heavy in the wild, which is why a female lays hundreds of eggs.
Cite this page
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Milkweed USA. (2026). Crab spiders and ambush bugs (Misumena, Phymata). Retrieved DATE, from https://milkweedusa.com/wildlife/crab-spiders-and-ambush-bugs/
"Crab spiders and ambush bugs (Misumena, Phymata)." Milkweed USA, 2026, https://milkweedusa.com/wildlife/crab-spiders-and-ambush-bugs/. Accessed DATE.
Milkweed USA. "Crab spiders and ambush bugs (Misumena, Phymata)." Last modified 2026-08-01. Accessed DATE. https://milkweedusa.com/wildlife/crab-spiders-and-ambush-bugs/.
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title = {Crab spiders and ambush bugs (Misumena, Phymata)},
author = {{Milkweed USA}},
year = {2026},
url = {https://milkweedusa.com/wildlife/crab-spiders-and-ambush-bugs/},
note = {Accessed DATE}
}