Keeping my fingers crossed for a baby boom for you - well, for your shrimp anyway. I keep thinking my cherries been eated only to find them under rocks. You must be completely flumoxed as to what happened. Best wishes on rebuilding the stock.
Maybe the reason for the insect being in the tank should be examined... (Raid?)Well, I found a wasp/hornet in the tank the next day in pieces. I am doubtful this caused it, but who knows.