New(ish) enemy of Coreopsis

(Last Updated On: March 28, 2019)
coreopsis beetle

Phaedon desotonis, a small, bronzy-colored beetle, defoliates a Coreopsis plant in Blanco Co. (Photo by Sheryl Smith-Rodgers).

Some of you may be lovers of the spritely flower called Coreopsis.  If so, bad news. A tiny leaf-feeding beetle with the tongue-twsting name of Phaedon desotonis has been showing up in occasional outbreaks around the state.  I recorded one in Caddo Mills, TX (Hunt Co.) this month two years ago, and blogger Sheryl Smith Rogers reported (and photographed) an infestation last week in her backyard in Blanco Co. (west of Austin).

Mike Quinn provides two more links to information on this native pest for those of you who would like to learn more:

Ed Riley, from the Department of Entomology at Texas A&M theorizes that this may be a case of an insect herbivore suddenly expanding its host preferences to new plants which were not previously on their list of favorite foods.  If true, it may take a little while for this pest’s natural enemies to adapt to find it on its new host.  Many natural enemies learn to find their favored prey by first searching their prey’s favored host plants.  This might be a way that some herbivores stay one step ahead of their enemies.

Let’s hope for the sake of Coreopsis that the predators wise up quickly.  If you are seeing this insect on your Coreopsis, please consider commenting on this article by describing where you have seen this insect occurring (include the city, state, county and date of observation).  Thanks.

3 Responses to New(ish) enemy of Coreopsis

  1. mike.merchant says:

    Observation by Amanda Schulz on varietal differences in susceptibility 3/19/2018:

    My husband and I have a large, established, National Wildlife Federation-certified pollinator garden at our home in the lower Greenville area of Dallas. We have a number of different Coreopsis plants that are coming back this spring, seems as though we have three different varieties for sure. There is one species that was being eaten to shreds.

    What is interesting is that the particular Coreopsis that it likes has a more glossy, lanceolate leaf (I don’t know the species), but it seems to be avoiding, at least for now, the bigger ‘Nana’ species that we have, and a more mouse-eared variety with small round leaves. I thought you might be interested to know this preference, because literally they are eating the glossy one and avoiding the others that are sometimes less than 2 feet away.

  2. mike.merchant says:

    This from Ken Steigman at the Lake Lewisville Environmental Learning Area 3-28-2019:

    “I happened upon an interesting beetle that I believe I have correctly identified as the coreopsis leaf beetle ( Phaedon desotonis), feeding upon none other than Coreopsis tinctoria in a wildflower area that I planted last fall.

    “The feeding larvae have destroyed small patches of the area and I am wondering if insecticidal soap or neem oil might work to control them before they get out of hand? Any advice would be greatly appreciated.

    “Also, under the scope the larvae are incredibly interesting in that they appear to have a defense mechanism I have never seen. When touched, they have several rows of glands along their bodies that they can erect. I am guessing that these glands produce some sort of chemical defense against predators…”

  3. mike.merchant says:

    This comment from Kelly Hooper in Arlington 3/11/2020:
    [We have] a large presence of the Phaedon desotonis (coreopsis leaf beetle) in Arlington Texas. I have observed hundreds of these beetles on 13+ coreopsis plants at my residence located in zip code 76015. In addition, I have also observed infestations at my work located 5 miles away in zip code 76006, on multiple Coreopsis. In both cases they were found feeding on only the Coreopsis plants, with no interest in any of my other plants (my garden contains a very large variety of perennials and annuals and these beetles did not touch any other plants but covered every single Coreopsis). A member of my gardening group also reported their presence 2 weeks ago on his Coreopsis in Wichita Falls Texas.

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