I quick Google turned up the following (see link).

It might be some sort of gall-forming larva.

Kevin

Here is a link that might be useful: Orange larva

Thanks so much Kevin. All of the heleniums have them as well. In the helenium they are all the way to the crown. Hundreds of them packed in there. I googled myself but never tried just orange larvae. The heleniums I only have four their getting tossed. The same for sun flower plants and heliopsis. Just too much can go wrong. I already am having to keep an eye on phlox and asters hoping they stay healthy. Phlox has been doing so well for a long time. I kind of wish I had not added the asters. Anyway I'm not sure if it's gall larvae but could be. It's closer than anything I found. Thank you again.

Patty

I wouldn't freak out too much. I know these are ugly, but keep in mind they are pests and not a disease. If you cut the plants to the ground and get rid of the stems and foliage, you've destroyed the adults that would have emerged next spring. No adults, no eggs and no larva next season.

It may have just been a particularly good years for this pest and that's why you have them. You may not have them at all next year. Just to be on the safe side, you could spray your plants next year with some non-toxic pesticide to kill any larva that may appear. Spend some time this winter trying to find out the best way to deal with it next season.

If you've ever wandered a field full of goldenrod in the fall, you'll find a huge number of the plants have galls. If you cut the gall open, you'll find a worm inside. Many plants have evolved to tolerate them.

Just for the heck of it, I'm going to try to remember to check some of my plants. Maybe I've had them all along and just didn't know it.

Kevin

You're right of course, last year it was the plant tarnish bug. This year no sight of them. The fields were in much better shape this year thanks to generous spring rains, so they probably stayed there. Yes different insects have their years just like weeds. Started to worry about bringing in to many new disease or insect prone plants. They did all bloom fine this year but I was seeing stem weakness, die back and browning in places. While taking a real good look at them I found these guys in the stems. So I'll take a deep breath and relax. Much thanks again.

Interesting thread/comments.

I'll be sectioning some aster and helenium stems from now on.

I've certainly seen galls on wild goldenrod stems, but, here at least, I've never seen galls on garden aster or helenium stems.

I have no galls either on any of the affected plants. The heleniums were the most affected packed all the way to the crown but not every stem. The aster Blue Autumn only had a few stems affected.