- Author: Kathy Keatley Garvey
Have you seen any overwintering milkweed bugs lately?
About a dozen milkweed bugs, Oncopeltus fasciatus, emerged from seclusion Jan. 2, 2022 in our Vacaville garden. The temperature hovered at 32 degrees that morning, but when the sun peeked out, there they were. Mating.
Little early, aren't ya, buddies? If you're waiting for the first milkweed seeds, get set for a long wait.
Jack Frost nailed what was left of most of our milkweed. So where are the colorful reddish-orange/black bugs overwintering? In our nearby cacti and succulents.
Milkweed bugs are known as "seed eaters" of milkweed, but actually they are opportunistic and generalists, according to Hugh Dingle, emeritus professor of entomology at the University of California, Davis. In a September 2019 Bug Squad blog, Dingle told us they will eat monarch eggs and larvae (milkweed is the host plant of monarchs), as well as the oleander aphids that infest the milkweed.
"Milkweed bugs will get protein from wherever they can find it," said Dingle, an insect migration biologist and author of the textbook, Animal Migration: the Biology of Life on the Move. They've been known to feed on insects trapped in the sticky pollen of the showy milkweed (Asclepias speciosa). And on nectar.
Dingle served on the UC Davis Department of Entomology faculty from 1982 to 2002, achieving emeritus status in 2003. National Geographic featured him in its cover story on “Great Migrations” in November 2010. LiveScience interviewed him for its November 2010 piece on “Why Do Animals Migrate?”
But milkweed isn't the only plant that these bugs breed and feed on. "The fascinating thing about milkweed bugs is that they will feed and breed spontaneously on Erysimum and Cheiranthus, two Brassicaceous genera that make cardenolides!" UC Davis butterfly guru Art Shapiro, distinguished professor of evolution and ecology, told us this week.
The amazing world of milkweed bugs and the plants they feed and breed on...
- Author: Kathy Keatley Garvey
Milkweed bugs gained the nickname of "seed eaters" for primarily eating the seeds of milkweed.
Actually, they are opportunistic and generalists, says Hugh Dingle, emeritus professor of entomology at the University of California, Davis.
They will eat monarch eggs and larvae (milkweed is the host plant of monarchs), as well as the oleander aphids that infest the milkweed.
We recently watched a large milkweed bug (Oncopeltus fasciatus) munch oleander aphids on a narrow-leafed milkweed (Asclepias fascicularis) in our pollinator garden in Vacaville, Calif. Between the milkweed bugs and the lady beetles, aka ladybugs), they absolutely cleaned off all the aphids, the first time in years.
Milkweed without aphids? Unbelievable! That's like macaroni without cheese, a pencil without paper, or a hammer without a nail. It's a "given" that if you grow milkweed, you'll get aphids. Some monarch butterfly enthusiasts kill the aphids with a soapy water mixture (which we've done in the past), but this year, we let biocontrol reign.
It worked wonderfully!
"Milkweed bugs will get protein from wherever they can find it," says Dingle, an insect migration biologist and author of the textbook, Animal Migration: the Biology of Life on the Move. They've been known to feed on insects trapped in the sticky pollen of the showy milkweed (Asclepias speciosa). And on nectar.
Dingle served as a professor at UC Davis Department of Entomology from 1982 to 2002, achieving emeritus status in 2003. National Geographic featured him in its cover story on “Great Migrations” in November 2010. LiveScience interviewed him for its November 2010 piece on“Why Do Animals Migrate?”
A fellow of the American Association for the Advancement of Science and the Animal Behavior Society, Dingle has done research throughout the world, including the UK, Kenya, Thailand, Panama, Germany and Australia.
Dingle is a former secretary of the International Society for Behavioral Ecology and past president of the Animal Behavior Society. He received the Edward A. Dickson Professional Award in 2014 to do research on "Monarchs in the Pacific: Is Contemporary Evolution Occurring on Island Islands? (See news story on Department of Entomology and Nematology website.)
