Did you see the root mealies in the soil?

tj

That sounds like rot to me.

Mealies don't actually consume a plant, in such a manner as to make one disappear as you describe.

However, rot, and or root loss (from rot) will make it collapse and depending on size, can make it seem to vanish.

They can shrivel up to nothing if plant was small enough to begin with.

eta: can we see pics of the surviving plants? Recommendations can probably be made to assist in their survival & or advise pest elimination.

Ok So it wasn't root mealy- it was just really old caked on perlite-- this is my second scare because perlite looks just like the residue of those bugs! im going to need to find a new soil mix it seems.

It also wasn't rot. I guess when watering the little cactus my shirt grazed it spikes and completely lifted it out the soil! I found it much later on laying on the ground. this would happen to me haha.. It looks pretty rotted to be honest though so I guess I will see what happens next.

I use perlite a lot since can't get pumice easily. I sift it to get rid of dust/very small particles.

Was it overwatered? Did you grow seedlings from the seeds? Any photos will really help...

Rita- i didnt sift and its causing some real problems. Its caking around my drainage holes looking like pest residue.

They look a little more green now then shown below.. i can post a more recent picture later. There are 4 of them and I did grow from seeds- but woof they look terrible haha. Hopefully they can be saved!

These are the updated ones