I have some thoughts.
I have hand paired polyxenes and oregonius respectively. Some of the time it seemed simple, other times they refused. I tried to think about
what the issues were, what time of day was it, had they been fed, how old were they?? Perhaps taking more notes would have been a good idea-
Possibly, I decided perhaps incorrectly that morning worked best, I do think that holding them for more than 10 minutes is a waste of
time. I don't recall if they had been fed or not, but I have learned a bit about butterfly nutrition since then, although I was using
hummingbird nectar with electrolytes. I'm not going to be using body fluids thank you, but might mix in some gatorade next time.
Different species pair at different angles, the age of the insects is also going to be a factor, and that seems to vary with species, if
it's an old male, sometimes that works better, other species work better if the male is fresh.
It could be they insects know they're not ready to mate, for instance, maybe they're missing some nutritional requirement.
Lighting didn't seem to matter, my room has ambient light from the windows and skylights.
I have some brevicauda in the fridge right now, and am waiting for spring when my fennel bush starts growing again.
It may just be too soon for the female, since she just emerged...