Been there done this.... more than once. This is what happens when plants are outside for the summer... or any time for that matter. I learned my lesson long ago when I almost lost a beautiful Echeveria 'Black Prince' to beetle larva. They just love to eat up the stem!!!!! Now I apply imidacloprid granules on EVERY Plant that is outside before I bring them in for the winter.

My plants have been outside every summer for almost ten years and I've never seen this. Disheartening to hear this is not uncommon.. Unfortunately I live in Nova Scotia, which apparently has some of the strictest pesticide regulations in Canada.... I can't even buy neem oil locally any more. Systemics are not to be found.

My Echeverias are having a rough time this fall... At least 5 have rotted off their roots. The plant looks fine until it becomes very wobbly in its pot. A few had already rerooted above the rot by the time I discovered it. I'm not sure what happened, I suspect I may have let them dry out too much,killing to roots, and they it rotted wheni watered..I don't think I will loose any species, but some nice specimens' survival is questionable. They are in gritty mix with perlite, turface and grit ( no bark).

Common occurrence for me too, just caught 2 just the past few weeks, think they are caterpillars. One burrowed into a leaf of a Pachyphytum, totally hollowed out the leaf with only the 'skin' left; another in the stem of an Echie.

These are similar to caterpillars but do not produce a chrysalis as would the larval stage of a butterfly. This grub will morph into the adult insect. Normally they wouldn't be active but because we create a false environment for them by "changing" their season, they come to life and eat everything in sight.

Bikerdoc,

How do you usually notice them? I just happened to move this plant and it was a bit wobbly in its pot....If it had progressed further, would the plant start dropping leaves or would they eat right though the rosette?

If not caught soon enough, they will burrow all the way up to the rosette. Usually the rosette will fall over. I've found two or three grubs disturbing my Black Prince. You found this early so you'll be able to root the rosette.

Thanks Bikerdoc

yes, this should reroot itself , in fact it had already sent out new roots from above the cavity Into the substrate. Plus it had three good sized offsets which were unaffected

This year was the first yearI had one damaged by beetles the plant was inexplicably declining I look under some lower leaves and saw many were chewed on and also observed a few small black beetles scurrying around the base of the plant. the most common destroyer of my echeveria outside are birds. there is a family of cardinals I believe to be the culprit. they single out one at a time and slowly pick it to pieces