What's That Bug? does not endorse extermination

Subject: Black and Red with White Spots
Location: 92595 [Wildomar, California]
April 19, 2014 4:11 pm
I just found this in my backyard and want to know if he will be bad for my vegetables, grapes and fruit trees. I’ve narrowed it down to either a Milkweed Bug or a Box Elder Bug… but don’t know.
Signature: Joseph Morabito

Small Milkweed Bug

Small Milkweed Bug

Dear Joseph,
You did a very good job of narrowing this identification to two similar looking species.  This is actually a Small Milkweed Bug,
Lygaeus kalmii, and we do not believe it will cause any significant problems in your garden.  Citations on BugGuide include:  “Adults suck nectar from flowers of various herbaceous plants, and also feed on milkweed seeds(?). Also reported to be scavengers and predators, especially in spring when milkweed seeds are scarce. They have been reported feeding on honey bees, monarch caterpillars and pupae, and dogbane beetles, among others. The Life of a Californian Population of the Facultative Milkweed Bug Lygaeus kalmii.  Adults mainly feed on milkweed seeds, but they often consume nectar from various flowers. Harvard Entomology.”

What's That Bug? does not endorse extermination
Location: Wildomar, California

2 Responses to Small Milkweed Bug

  1. Jean Anderson says:

    Its February 14, 2016 and I’ve found a dozen or so of these bugs on my Milkweed plants.Small Milkweed Bug, Lygaeus kalmii,
    Your comment about these bugs you say that they like the plants, but do they eat the caterpillars ? You also mention that they are”scavengers and predators, especially in spring when milkweed seeds are scarce. They have been reported feeding on honey bees, monarch caterpillars “… Should I do anything or just let nature take it’s course ? Jean Anderson, Westminster, CA

    • bugman says:

      We would not put anything past a gang (it can be formed from aggregation) of Seed Bugs. We imagine they will eat what they must to survive, and if no milkweed seeds are available, they might turn to Monarch Caterpillars. It would stand to reason (But will it stand up to scientific scrutiny?) that the Small Milkweed Bugs, which ingest the toxins in milkweed, to be immune from the toxins stored by the caterpillar. We would be more inclined to consider these opportunistic feeders to take advantage of fluids that remain in dead insects.

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