Those pictures are stunning, Jeff!
I don't know of any markings that signal whether a question mark is male or female. My Florida butterfly gardening book shows pictures of each sex, and the only difference I can see is that the female is bigger and slightly paler overall - without seeing them side by side, I don't how you'd figure it out.
Question marks lay their eggs on the underside of leaves, sometimes singly and sometimes in interesting stacks -
{{gwi:482514}}
Sherry

To add to Sherry's commmments... since the sexes are similar, behavior or best yet inspecting the abdomen for size/shape or claspers is how I'd sex it. The one you picture is the summer dark form umbrosa, and yes, they are super pictures.

Jeff;
The males tend to patrol a lot. I mean a lot and really check you out. Wave a small dark sock or net and see if it flies to you. A lot of times when I am out with my net the males will come right to me. Guess they think I am the competition. Not that I can catch them. There were two puddling around me the other day, I had fun chasing them and they had fun flying circles around me. I swear I heard bart simpson shouting "ha ha". I don't think the females do this but then I haven't caught one to check it.

On our plant they have been laying on the tops of the leaf, which is weird. They don't seem to be laying on newer growth but not the largest leaves either. Keep checking because it seems everything likes to eat hops leaves.

Keeping my fingers crossed for you! I hope to raise some this year too.
-Elisabeth

QMs use elm in my yard primarily the seedlings and saplings 4 tender foliage. So far as i can tell they have completely ignored the hops vine. i did find 1 on false nettle one year, which is also a host 4 them as well. u just gotta figure out what their favorite is.

susan

I suggest looking for eggs when it is very sunny. More than once I've noticed a single egg (stacks are easy to see) because the sunlight made it sparkle.

KC

Incredible pics, Jeff! I'm wicked jealous! :) Congrats on the visitor--hope you get some eggs soon.

I love that the eggs sparkle!