Monday, April 9, 2012

Beetle infestation!

Something's out of balance!

Last week, we pulled up seven bags of invasive Malta star-thistle. And we're not done yet. But at least, we've gotten the bulk of the nasty stuff out. Saturday evening, while I was monitoring areas along the street, I happened to notice beetles. Tiny bronze brown ones atop the foliage. On the ground. EVERYWHERE. Thousands of them! I went for my camera and took some shots. As I squatted down, now and then I'd hear them topple off the leaves and fall to the ground. It sounded a little like rain. Strange. We've never seen anything like this in our Wildscape.

To help understand what's going on here, I emailed entomologist Ed Riley, a beetle expert at Texas A&M University. Here's his reply:

"Your comment 'out of balance' is appropriate. This beetle is Phaedon desotonis Balsbaugh (Coleoptera: Chrysomelidae). It was named in 1983 from a single specimen from NE Alabama. It was later found at other southern Appalachian localities, where it was found feeding and breeding on a rather uncommon host plant, a Coreopsis sp. (Asteraceae). Now why is it so common in Texas and elsewhere? This is apparently a case where a relatively rare plant-feeding insect species has “jumped” from its rare native host to related common hosts and is now expanding its geographical range. I have been sent specimens from wildflower nurseries, where this beetle was reported devastating cultivated Coreopsis. Coreopsis–or related genera–are also very common roadside plants in many southeastern states. The beetle is now recorded from several states, including AR, FL and TX, and I suspect it is found in all intervening states, too. This year, I have noticed very large numbers in the College Station area similar to what you show in your images. The beetles we see now (April) developed this spring from eggs deposited from adults that overwintered last winter. I suspect population numbers will remain high for a few years, then will probably adjust downward, in much the same way most populations of new exotic insects fluctuate after introduction.

The adults are "not likely to eat anything that is not Coreopsis or a closely related genus of Asteraceae. I don't know if adults will feed before aestivation [dormancy]," Ed added.

He also sent this link:

Well, duh, we finally realized that these beetles are EATING OUR GREENTHREAD! The flower species belongs to the Asteraceae family. So awhile ago, James stomped as many as he could. So much that his feet were black (he had on slaps) so he had to rinse them off outside. Yuck. I didn't stomp, but I did pull star thistle for an hour or so.

Dang. It's been a tough spring in The Meadow.


I am very dismayed to report that these beetles are forging their way toward our back yard. They decimated most of our greenthread. Some are blooming now. The vegetation that they attacked stands browned and bedraggled. I found them on species that are other than coreopsis. Their MO is to drop when you approach. Which makes it hard to smash them with your foot.

I looked up Phaedon desotonis on and found that this post has been referenced! SEVERAL TIMES! 

One of the references on that page is...

Internet References
Photos of central Texas outbreak - S. Smith-Rodgers, 2012 (with comments by E.G. Riley)

I also found another link to my blog with a photo of mine (which technically, they should have asked for my permission before posting it): "New(ish) enemy of Coreopsis."


Rock rose said...

I remember seeing that last year on my coreopsis. Nasty little blighters. Glad to know what they are. I will be on the look out for them. What other plague do you think will come next?

Sheryl Smith-Rodgers said...

Gee, beetles. Bastard cabbage. Star thistle. NO MORE plagues!! :-)

CWPickens said...


Frivolities said...

Just found your post while trying to ID this little beetle......we have what seems to be an infinite number of these pests. They are only on a native vining plant that I've not been able to identify (we aren't really good at gardening). This vine just appeared one day and it tries to take over our yard. It seems to be a native ground cover which flowers each year with pretty little white flowers and it seems to spread underground. It just pops up in random places.

This vine will completely cover honeysuckle, rose bushes, really anything and it is quite prolific this year with all the rain here in FW.

Yet, these beetles have almost killed it off.........they apparently just suck the life right out of the plants. But, the beetles are not interested in any of our other plants.

Just thought you might be interested in the info!

Sheryl Smith-Rodgers said...

Thanks for sharing! Sounds like you have a different species of beetle because ours feeds only on coreopsis, according to experts I've contacted. The beetle numbers have declined to just a few here and there. My two coreopsis in the back yard survived. Barely. They are putting on new growth. Thank goodness!

Anonymous said...

Greetings Sheryl,
I may have encountered some larvae in my butterfly garden today. I wondered, have you noticed the behavior of the young larvae on the flowers? Specifically, I have tiny - first instar size - caterpillars that settled into the centers of Coreopsis blossoms. Each larva folds over a couple of petals, securing them with silk. This is a fine protection against wasps, but the affected blooms are easy to spot. If this is Phaedon desotonis, I could clip off blooms and pop them in the freezer!
Thank you for your time. Warmly, Sally

Sheryl Smith-Rodgers said...

Hi, Sally:

I don't recall finding any silk associated with the larvae. Did you find my other post with photos of them? Go to The larvae ate the blooms AND stems, just like the adults. I found two more adult beetles yesterday on my coreopsis. Grrrr! Keep me posted. Hope you don't have an infestation!!

Theresa said...

I found a pile of these in my garden in Mesa, Arizona about a week ago. Late June 2016. In my 50+ years here I've never seen them. I do not have any Coreopsis in my garden, but they were clamoring on my Cosmos which can have a similar appearance. I have not seen any plant damage at this point.

Sheryl Smith-Rodgers said...

Hmmmmm, that's interesting, Theresa.....

Anonymous said...

Unfortunately, the Lanceleaf Coreopsis in our backyard in North Texas has become infested with these beetles during the last month or so. Has your Coreopsis survived? Has it been infested in the years subsequent to the initial outbreak? Wondering if we should just replace the Coreopsis with something else.

Sheryl Smith-Rodgers said...

Yes, our native coreopsis survived. And we still get the beetles but not as many. I go after them by hand. I put a bowl of soapy water under the plants and sweep my hand through the leaves. The little buggers drop as a self defense....right into the water!

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