Looks like it could be red aphids. You can use neem oil or gory oil. Someone else I'm sure will chime in

Looks like scale to me. I don't think your mushy arm is due to such a low titer of insects in your picture. I get mush when I water inappropriately in summertime here in AZ, but don't know what's going on with yours. You could probably just use a q tip dipped in soapy water to remove individual scales since your infestation seems low. I treat my agaves and ascleps with imidacloprid once/twice a year.

-Ming

Ok, thanks, any suggestions help. I water only once a week and they stay dry for the rest. My semps are also turning yellow, they are suspended in the air though. Since they are a clump, the ones in the ground are good but the ones in the air are yellow and I think drying out. The semps are in my gravel, lava rock and succ soil, my best and fastest drying out soil. Its one problem over the other. Its going to be hard with a Q tip, I see only one atm and his colour seems washed out. I sprayed the plant with horticultural oil yesterday. I water the plants every sunday. I will keep a close eye, if I see insects, I will spray soapy water over the whole plant.

I'm zone 5 here in Wisconsin. I would think/worry that once a week watering is going to kill that plant. I have succulents that are lucky to get watered once a month. The only ones I water every week are the ones I have in a gritty mix. This pic is my Huernia that I haven't watered for three/four weeks now. It hasn't told me to do so just yet. Succulent love to be neglected (aside from infestations and disease) could be your mushy problem, could be something else.
Chad

Definitely looks like scale to me.

Personally, I find that zebrina can take quite a bit of water. Bikerdoc waters his more frequently than I do, I suspect, and his grow far, far more vigorously than mine. (That is not to say that overwatering might not be the issue. Just that one shouldn't assume that it is.) Mine get watered once a week usually and are in a 50/50 peat/large grade perlite media to boot.

Darn, I have made a soapy spray and I did spray them yesterday. Ill keep a close eye on them. I water them once a week and the pot dries out within a day, so Im kinda confident its not over watering.

Soil can and should stay dry between waterings...
-Ming

Mine is potted such that the pot is in a catch tray/container with about 1-2cm between the bottom of the pot and the bottom of the cache. Much to my surprise, it has sent roots down into the cache where they wind up sitting and growing into the water area. The soil area, however, does still get quite dry between waterings.

Well, I didnt water it today even though its dry. Will go 2 weeks without water, I hope the rest of the plant stays fine. I have not seen any of the red bugs yet, the one that was on the much turned brown because I sprayed soap on it and the rest of the plant. Lets see how this goes.