I recall that while recently reading Doolittle's treatise on queen raising (during the late 1800's, he stated that it was easy to release a virgin into shook bees in a broodless hive. I think that releases into smaller colonies would boost success rates, too, even with brood. It may be even better with no eggs and a very fresh virgin. They don't seem to store very well in an incubator or hive nursery.
I am interested in working with virgins, as we have extra cells quite often and I'm still trying to find a technique with Jz's Bz's cups to let the queen hatch out into a vessel. I had considered Vera-Yordy virgin queen introduction system. They are a bit expensive, but I will give them a go.
When we do release virgins, we generally like to spray the bees with a hand sprayer with a light syrup. I think an addition of scent helps, like lemongrass. It's better than smoke.
We get so busy that it is difficult to find the time to do any real research.
Yesterday we did our first prep on the gulf coast for our first graft today. Now it's 7 days a week for quite a while, and then it's two days a week after that.
The weather is about 10 to 15 degrees below normal and rainy. We had snow a couple days ago. The locals stopped their cars and took pictures. Lot's of weather in the 50's F for highs. Usually about 62 F for highs.
Nonetheless, the bees look good, and neither rain nor snow will prevent us from raising good cells and strong hives with a good feeding program. Lots of drones hatching out right now (perfect). I predict perfect weather with light wind below 5 mph in the mid 60's or higher( in my dreams).
The rest of our crew arrives in a week to split in advance of the cells hatching.