I have seen stem borers only rarely on tropical sages. I'd expect them to be more common in North Carolina than Missouri

I took a picture of one. This is the largest one I found. It was about an inch long or maybe a little less.

Those yucky darned cats that we DON'T want! I have some kind of moth larvae on mine every single year. I think they must be overwintering on the B&B because of their consistent appearance each year. They eat the new growth and flowers, so I have few, if any, flowers. I am just going to have to get rid of this plant, unfortunately. I've given it 4 good years in the garden, and it is just not worth keeping it since it doesn't even get a chance to bloom.

I can't/won't use any kind of caterpillar control because I butterfly garden. I will probably do without a B&B for a year or two and hope the caterpillars disappear, then replant it in another location. So sad......

Seems like this particular plant is just prone to pests.

Susan

Christie:
You should be able to use BT (Bacillus thuingiensis)to
take care of your problem.I will not harm any other
insects good or bad. Just your Caterpillar.
Art

Is BT safe for hummingbirds? I guess I could cut off the flowering stems for awhile so I wouldn't have to worry about them getting poisoned. I don't have hummingbirds this time of year anyway.

I have also seen some smaller larvae that burrow into the flower buds and eat them before they get a chance to open up, but the one above is larger and was inside the stems down closer to the base of the plant.

I signed up for Garden web a few months ago, and then couldn't get on, figured out my firewall was blocking it. I'm so glad it's fixed cause now and I found this thread. I've had the same problem with my Purple Majesty and I'm in Central Florida. Found the same caterpillar on it. I too garden for Hummer's and Butterflies and Purple Majesty is hands down a favorite of the hummer's. Especially when it gets really tall and full of blooms so am looking for something to control that won't harm the hummer's or BF's.
mj

Welcome mj! Glad you were able to post. I don't have Purple Majesty. Looks beautiful in the photos I've seen of it so I hope we're both able to save our plants.
There was another wilted stem on one of my Black and Blues yesterday but I didn't find anything inside the stem. The good news is that it was the first wilted stem I've seen for several days so maybe whatever it was is dwindling already. I have some blooms but they're not at their peak yet.

Mine's doing better too,now I'm wondering if it is just the blasted hot weather. We've had alot more cloud cover and a bit cooler, ( still hot but not the 97-99º. I'm watering more now too. I'll have to go look up how to post pictures.

Re: stem borers and BT. The caterpillars must be able to ingest the BT for it to be effective. If the caterpillars are inside the stems, you won't be able to reach them unless you cut the stem open, and once you've done that, the plant is already damaged so it would seem to be redundant at that point.

Christie, I don't use BT in my garden because other caterpillars (wandering) could ingest it as well and it kills all caterpillars that happen to ingest it.

I feel your pain. The nasty caterpillars are back again this year, and have moved to include other Salvia that I have planted out as well. Sigh..... Don't know what I am going to do to resolve this problem. Just hope they survive the attacks. I have exactly 3 blooms on the B&B and no signs yet of other blooms coming up. I am trying to hand pick the ones I find, but they are small and they hide during the daytime hours.

Good luck!

Susan