Thanks for the reminder Carolyn.
I have to add that, as soon as I posted, the bumblebees made a liar out of me.
I went out to check fruit that are ripening on my row of F2 cherries this morning, and there they were, diligently doing their business. Later in the day, I saw them at it again. Maybe because the prevailing wind changed last night, I really don't know.
In any case, I'll be sticking to the seed from plants in the greenhouse, if I want to be certain they are not cross pollinated.