That does look like scale on the last plant. Not sure about the white stuff. Almost looks like a fungus or yeast. Hard to tell while the plant is wet.

Thanks - re: scale looking at it dry and pics of scale from the interwebs, I agree with you. Too bad as that is a pest Captain Jack's doesn't fight.

However, reading about this topic more, I think any kind of spray-on product is going to fail in this scenario, as the plants are so tiny and closely packed it'd be impossible to get to all of their undersides except maybe by constructing a hood and using a fogging aerosol. (Note if you have bigger sedums, I found horticultural oil spray, made from highly refined vegetable oil, seemed to be the most recommended product type.) I could do the fogging enclosure. But maybe a systemic would make more sense; especially as it is pretty much guaranteed that re-infestation will happen at some point, as this is outside.

So I'm looking into brands / specific systemic insecticides - if anyone has product suggestions, let me know.

If they are outside, other bugs should keep them in check and they'll die over the winter.

I believe that white dage is from your spray. Scale doesn't have that affect.

Yeah I think you're right about the white; looked again today and it was gone. The scale on the last plant if there is subtle, but how about the numerous non-subtle brown spots, some of which look eaten into the leaf? Some kind of mite? If so, here's the combo I've come up with:

Acephate - Amazon: "97UP 1lb bag Generic Orthene Insect & Fire Ant Killer" - http://www.ext.colostate.edu/pubs/insect/05507.html says "Insecticide with some effectiveness against spider mites. Systemic."

Forbid 4F - eBay: "Free Forbid 4F Miticide Spiromesifen 1/4 OZ free gift when u purchase 3 pipettes" - "Like Avid, it is translaminar. The active ingredient, spiromesifin, while not systemic (i.e., it does not move through the plant’s vascular system like, for example, Merit does), is absorbed by the plant’s leaves and will move from the tops of the leaves to the bottoms where the mites feed."

A lot of the more mainstream systemic products use Imidacloprid, and while they don't claim to work against mites, they also don't mention that one reason that spider mites become a problem is insecticides [such as Imidacloprid] that kill their natural predators.

I "caught" one of the suckers! I think some kind of spider mite - anyone know which one? Also elsewhere suggested holding a white paper under live plants and shaking to check for spider mites.

Just how small is that thing? I don't think you can photograph spidermites with a regular camera. They are almost microscopic.

That looks like a tick to me.

It's about 8mm back-front, 4mm side-side, 2mm legs.

So you are right, as Google tells me spidermites are less than 1mm, usually around 0.5mm

Drat, back to not knowing what to do :-/

I see some mechanical damage on few leaves in your last post; they look like something chew on them, or damage done by falling object - twigs/branches from trees around or somethin similar. Looking at the last photo in your original post, I would also think it is some scale present. I don't see much of it to warrant sprays you mentioned - but it is your call. I would use rubbing alcohol spray and make effort to get it on underside (you can 'lift' the plants enough to be able to spray).

The 'mite' does look like a tick or something similar. Being outdoors, planted in tree trunk (great idea!), there could be so many bugs there - good and bad ones. It is obviously very organic, trunk very slowly decomposing - must be heaven for them.Unless it is constantly very wet, it should be pretty good for many plants.

How long has that sedum been planted in same spot? Maybe it just needs a haircut to rejuvenate? Is it in full sun? Where are you located - general location?

Rina