Just built my first mason bee house and have them the first year. My question is how long can I delay putting out cocoons next year so I can coordinate them to a later time when melons start flowering? Will the Pupae survive the longer stay in fridge say into mid summer before being introduced to warm temps?
If they're mason bees and not leaf cutter bees, they are already formed in their cocoons when you received them and can stay in the fridge hibernating as long as they have enough moisture, but I am not sure how viable they are over a year. I put mine out once our daytime temperature is consistently 50º or above.
I don't have any experience using them to pollinate melons - they tend to like fruittrees and berry bushes. There are limits to the type of flowers they are able to pollinate because of their physiology and their ability to travel; they don't travel as far as European honey bees, but they pollinate more flowers. If there isn't sufficient food, they'll try to find a place that has them that's not your yard .