where are you .. do you have IDs on the plants???

you might also try the cactus and/or succulent forums ... ken

Hello Ken, Thanks for your reply. I live in Netherlands. Hmm, those plants were bought from several online shops.

Update: I made some new potting mix and repotted almost all of them with 7-8 hours... I just hope the worms won't get in the pots again.

Hello Ken,

I think there was something in the soil mix that can decay... and probably I gave them a bit too much water. Since they are all sitting indoor, could be that there was not enough ventilation to dry up the potting soil. Perhaps some roots were rotten.

God, I hope they won't come back again. I used some potting soil, pumice， akadama and some perlite to make the potting mix.

They are vine weevil larvae and they are eating the plant roots. Very common problem in pot plants, especially from less than reliable vendors. You need to check all the roots and soil.

Thank you, I have changed all the soil for my plants. I also checked their roots and I didn't find more of them. :) I hope they will be fine now. If that happens again, it means there are eggs in my soil bags...

At night when the room has been dark for a few hours turn the lights back on and see if there any adults about. (Google has images). There are chemical soil drenches available if you want to go that route. Vine Weevils