Q: I saw lots of these bugs at the community garden this morning. They are massed on the open pods of a vine-like plant that has grown up the chain-link fence. The pods are about 3 inches long, brown-gray, and with with a tail or point. When open, they release a mass of cotton-like fluff. What the heck are these?
A:Β They are milkweed bugs (Oncopeltus fasciatus), and the plant is climbing milkweed vine (Funastrum cynanchoides). In the photo you sent, I see mostly nymphs. These young bugs do not have fully developed wings. Instead, they show wing buds, the two small, black, miniature, wing-shaped parts on their backs. There is one adult in the photo, showing fully developed wings with a black stripe across the middle of the body.
Like monarch and queen butterfly larvae, these milkweed bugs are protected from predators by ingesting the milky sap from this plant. The sap contains cardiac glycosides that can harm predators. Their red color gives the warning to potential predators that they are hazardous.
Since these insects stick with that plant, and that plant is probably not what you are growing in your community garden on purpose, what you do about them is a matter of preference. Some consider the milkweed a weed, while others like to attract butterflies.
Peter L. Warren is the urban horticulture agent for the Pima County Cooperative Extension and the University of Arizona. Email questions toΒ tucsongardensage@gmail.com
