Mason Bees mating

Did you know that female bees can chose the sex of their offspring? Female eggs are fertilised, males are not. Usually, female eggs are placed at the far end of the nest cavity and males eggs in the cells nearer the entrance. Males of a lot of species of solitary bee species emerge before the females, mainly so they can be waiting for virgin females to exit the nest and mate with them immediately. It therefore makes sense for male bees to be in the outer most cells.
Weather conditions play a big part in emergence timing.

Leafcutter bees pass the winter as pre-pupa, finally developing into adult bees in the spring. Bees like the red mason bee Osmia bicornis pass the winter as adults, if you open a cocoon of this species in February the bee will be sitting there and fly off fairly fast.

If you have used wood with holes drilled these may also contain larvea from leafcutter and mason bees. Although you may not be able to see them, they may be at the back of the tube.

Any canes which appear unused may still be used at the rear of the cane so do not discard them.

Cut new canes, use rolled wrapping paper, drill good clean holes in timber blocks, do not use treated timber.

Solitary bees will pollinate more flowers than a honey bee.

Mason bees will leave a gap at the end of the tunnell/tube blocking the entrance with mud with its brood a good inch or so behind.