Aside from the random flights of smaller species in the foothills every time we have a heatwave, it's mostly just desert mating flights left now. Those queens are fairly easy to catch, since most don't fly until it rains pretty good, and they can be dug up for a few days after.
One of the exceptions is Camponotus fragilis. I have only caught those while they were running around at night, and not from founding chambers. Most are only around bushes, and they will fly with a very small amount of rain. The one time I caught Novomessor cockerelli, we never really saw any of them digging nests either; they all just seemed to vanish once the sun came up.