What is it with the european mantis, hatched ooth put all nymphs in small plastic geo ( about 100) with net curtain on the top some vermiculite in the bottom to keep a good humidity. Sprayed them nearly every day. (Not with fly spray with water lol!). Fed them well on fruit flies and micro crix but slowly over a period of about 15 days they have slowly dwindled down to about 15 is this normal for this species or did i do something wrong?......