was it a liquid that came out? i think if you squeeze them too hard the produce a liquid.
and yeah they bite. i can hear them chewing on the mesh inside the cup, and they always attack the tweezers.
one thing i've learned is that when i order them (even 1 cup) i need to order extra food! they always finish off the food before i can feed them all to my beardies, then i have to throw a bunch of veggies in with them and hope they eat those instead of each other!
Mr Dargon will only eat 1 big one, Tasty Treat will eat until she explodes :/
as for pupating, they can't unless the bury themselves.