Where in southern IL are you located?
Personally, I don't have a too late for swarms, however they "arrive." I try to take my losses in the fall, so any weak swarms or colonies are combined. The question is if it's your intent to overwinter any swarms you catch without combining? Then as Greg points out, you'll need time for some TLC to get them strong enough for winter.
For me, late July swarms usually seem to be weaker after swarms and likely to result in a combine or at best a nuc for winter.
The flow in my area wanes mid June, maybe into early July; your odds of trapping swarms likewise wanes; but as "they" say, never say never.