This is at the end of the report
'When virgin queens are used, our results indicate that
the younger they are the better, but that virgins
3–4 days old are only slightly less successful
than virgins 0–1 days old. This suggests that
virgins can be sent through the mail provided
that they are sent on the day of emergence, that
the mail is swift (one or two days), and that
they are immediately placed into queen mating
hives on arrival."
I think if you tried to ship one day old virgins, you'd end up with several mortalities. You'd have to pack that shipping box with lots of bees to keep the young virgins warm.
I've had older virgins alone in roller cage (No attendants) I didn't have room to place and forgot them in my pocket of my bee jacket. Found them the next day after sitting outside overnight around 65 degrees. Still active and hardy. If I did that with a day old virgin she'd be dead within hours-if not sooner.
I do usually place my virgin queens the day of hatching. But unless the day is HOT, I always have a small disposable hand warmer in my pocket with them. I also have an insulated lunch box I'll load up with cages filled with young virgin queens. A single hand warmer in with them and I can take my time collecting mated queens and replaceing them with ether cells or virgins.
If I collect a mated queen and only have virgins to replace her, I'll just let the roller cage sit on top the frames for a couple hours before releasing her. Overnight if the weather is warm enough and the bees will cover her. That way they don't need a queenless period and they don't start any cells of their own.
A couple newly made mating nucs with virgins in roller caged set on top.Cover with a well insulated lid.
Here you see what I commonly carrry in my pouch during the summer:
-Shipping cage that has attendants always contains a mated queen.
-Shipping cage without attendants always contains a virgin queen. I use this is I want to leave them caged overnight in a nuc that ether doesn't have room on top the frames for a roller cage, or the nuc is too small to keep that virgin warm. I wil then slip the shipping cage between the frames as standard.
-Roller cage with a capped candled queen cell & roller cage with a virgin queen.
I like roller cages for direct releasing over JZBZ shpping cages. The opening is far larger and you can more easily control the virgin's release & direct her down between the frames-so she doesn't make her break.
Hand warmers I use on occasion to keep cells and virgins from getting chilled.