It looks like just one out of the three is going to end up hatching. And of course, I missed it!
I noticed the empty husk the morning after my son's big birthday bash, which we hosted here. So the one that did make it flew on his special day!
I had noticed a large thin bug that looked like a hugely over-sized mosquito on one of the others. It looked like it might have been probing in through the top...do you think this bug might have harmed the ones that aren't hatching?