Friday, May 4, 2012

More on the blasted beetles

What's left of one of two coreopsis in our back yard.
Oh, perish the day last month when I first laid eyes on thousands of metallic brown beetles (Phaedon desotonis) that covered our greenthread in the Meadow! Since April 9 (and likely days before that), they've marched across what was to be a beautiful sea of flowery gold this spring and decimated the greenthread, both plants and blooms. 

From there, the incorrigible fiends crossed land barren of greenthread to find and latch onto two coreopsis plants in our Wildscape. Yesterday, James tried spraying deer-resistant mist on the plants. Then he sprayed soapy water. Awhile ago, I just happened to discover that the beetles have taken refuge on the underside of live oak leaves on the ground below. 

Oh, ye dratted insects of ill repute, BE GONE BE GONE from our peaceable habitat! I hereby banish you forever from our Wildscape! Alas, more coreopsis plants live on the OTHER SIDE of our back yard. Several beetles have made their way over and found them. Argh! How do they DO THAT?

I found LOTS of beetles on leaves and will likely find more.

My method of attack is to find the beetles (on the foliage and now on oak leaves) and drop the beastly invaders into a big bowl of soapy water.

Yesterday, I found this bug (Perillus splendidus) EATING one of the beetles.
So CAN we get rid of these destructive beetles? Ed referred me to Bart Drees, a professor of entomology and extension specialist with Texas AgriLife Extension Service and Research. Here's what he advised:

"Sheryl, The larvae look like some species of leaf beetle (Coleoptera: Chrysomellidae) similar to the yellow-margined leaf beetle or one of the flea beetles. It also looks like the damage may be beyond trying to save the plant leaves. Organic remedies for beetles used to include rotenone sprays, but few rotenone products remain. A strain of Bacillus thuringiensis called 'San Diego' has efficacy on beetles. Insecticidal soap spray may eliminate small, early instar, larvae. However, high pressure water spray could also knock of the larvae temporarily. See"

We have a sample of the beetles and larvae ready to give entomologist Ed Riley at Texas A&M University. "I would like to place vouchers for your observations in the TAMU Insect Collection," he wrote me. "I suspect we will not see numbers of this beetle like this again or maybe only for the next few years."


The greenthread survived and rallied! This past week, the plants have been blooming in profusion. On a side note, I found two or three dormant beetles under leaf debris in back yard beds Sunday, June 3. Darn!


Curious One said...

I would love to know if you have had any more porblems since then. I just had a huge hatch in my yard this weekend and want these beetles out of my yard ASAP! I would say I have millions, but that might be an exaggeration, so go with hundreds of thousands. So far Ive killed about 100. And they decimated my coreopsis within 2 days. I know they seed and the roots may survive, but what happens next year when the cycle starts over? Thanks for any advice!

Sheryl Smith-Rodgers said...

Not really, sorry. Last year, I just kept fighting them by hand. See Seems like one year I tried spraying vinegar/water on them, but then I think you kill other critters too. Maybe try my sweeping technique that I used last year? I think it did put a dent in their numbers. Good Luck! Keep me posted!

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