Last summer was our first year putting out various design bees "houses"both tubes and holes) and we got a good number of filled nests. We waited till late Sept to collect cocoons(here in N central MN hard freezes already) and we were surprised that around a third of the larva looked fully grown but had NOT cocooned. Is this normal? Chambers had been sealed off all summer. Anything we can do to help them fully develop this summer?