Some kind of borer ruined my shastas

Three of my shasta daisies died this year. I assumed it was due to poor drainage and root rot, since they are planted in the lowest spot of a bed sloping down to the retaining wall that lines my driveway. I didn't worry too much about them since I have to divide the healthy ones anyway and was just going to use the divisions to replace the others.

But today I finally looked at the roots and crown and found these. Any ideas what kind of borer? Strategies for getting rid of it?

Thanks in advance,
w

I can't see your image other than that it looks to be a milky white color so I'm going to try a shot in the dark based on your description of this being some type of a borer that is in the stem that I can see photgraphed above- please look up European corn borer (Ostrinia nubilalis) and see if possibly that's what you have devouring your plants. ECB doesn't just attack corn.

Borers are tough to get rid of with chemicals. If you can nail down what you have, there might be a biological control out there that would be far more effective than chemicals but biological controls are generally target specific and you really need to get a positive id.

Thanks for you message. I've re-cropped the photo to get closer in. It looks white with two antennae and multiple tiny legs. I didn't notice the tinier things that look like grains of sand when looking at it in person the other day. I'm not sure what those actually are. This is a piece of the root and crown my husband cut open since the little bugger had gone inside. Camera shy, I guess.

I'm thinking I might dig out all six of the shastas, pot up what looks healthy (if anything does), and then try to deal with the soil if possible.

This has been a bad year for diseases and pests in my garden for some reason.

Thanks.
w

No, that's not Ostrinia nubilalis. I think somebody else is going to have to take a stab at this. Doesn't look good though.

Thanks. You're right. It doesn't look good at all.

Gardening is about change, though. Right? (She tells herself while trying hard not to stamp her foot at the loss...) :)

Have a good day.

w

Could it be a rose stem sawfly larva?

http://www.forestryimages.org/browse/detail.cfm?imgnum=3066052
http://www.forestryimages.org/browse/detail.cfm?imgnum=1326119

I don't grow roses, roses hate me. After doing a little bit of poking around on the internet for that bug, I'm really glad I gave up on roses long ago as that's just one more pest that would have found its way to my house to devour any roses I tried to grow. Sheesh, is there anything roses don't get?

I'm not familiar with the Hartigia trimaculata you found but it's evidently a stem borer and what you've photographed is an insect damaging a distinctly different part of a plant so I'm thinking H. trimaculata probably isn't your culprit.

That's a good point. I inherited roses when we bought our home. I also inherited the rose borers that have made them their home. I've managed to get a handle on that by sealing all cuts. Glue sticks are my friends. :)

I think it's time to try the extension agent. Fortunately, the one for my county is a bug specialist.

Thanks,
w

Please come back and share what you learn!

I heard back from the extension agent today. Apparently it's a millipede. They start out light colored and get darker as their exoskeletons harden. They don't feed on living plant tissue, although they do eat dead and decayed matter, associated fungi, insects, and insect eggs. So the shasta daisies likely did die as a result of root and/or crown rot, and the millipedes are not a worry.

Now, I've really got to do something with the drainage problems in my beds with retaining walls. :(

w

Did they give you the Latin name of this millipede?

No, he didn't. Pretty much just what I wrote and a comment about how many legs it had.

bummer.

I can ask when I write back to thank him.

Please do!