My Mason bee farm started over five years ago,after a co-worker introduced them to me.I’m not too far away from Crown Bees and that’s probably who supplied the initial little box of about a dozen,that was bought at a local hardware store.
From that first group,there are probably hundreds.There may be some locals mixed in.
A forum member in Arizona was having trouble starting his,so I sent a bunch,but it sounded like they didn’t stay around.
Where are your cocoons kept outside,just before they hatch?Is that the plastic tray?The house I have,has a lid on top and some holes for them to crawl out of.
For what is worth, the mason bee condominiums are not the greatest approach. In nature they are solitary bees, putting them that close together makes them prone to disease and the dreaded bee mites. Is like setting up a buffet for those tiny bastards.
I harvested the cocoons today and here is a photo of them.They still need cleaning.Probably 150 of them.
I didn’t clean the boxes last year and noticed more dead ones and also small eggs from another insect.
They may be active in your area,a month or more before mine.
That’s an interesting question,about the bees in rain.Something I haven’t paid attention to.It seems by the time temperatures are warm enough here,the precipitation fades.
Sometimes,I did see a few of them,waiting inside the box holes,during colder days.Maybe that’s what happens during heavy downpours.
I got some mason bees a couple years ago & need to check the box. They have been active (blue masons) when apples bloom in eastern WA. The green are active the following month when my thornless summer bearing raspberries bloom - along with plenty of bumbles and solitary types throughout the season.