It's been my experience, whether your hiving a swarm, or a package of bees, they are looking to get going--they know whether you do or not, that the clock is ticking, and not in their favor--is why they work with a fervor to construct comb, and start brood rearing operations. Is a old saying goes like--a swarm of bees in May is worth a bale of hay, a Swarm in June worth a silver spoon, a swarm in July isn't worth a fly. While thats a bit of understatement, has a bit of truth from particularly to a commerical beekeer--in July a swarm you will have to feed and feed heavily, to help them along, most areas have a fall nectar flow of some kind, in many areas the flows are quite heavy ( depending on the weather ), but all this is tempered by the spectre of fall and winter and the comming cold weather. A mid summer swarm will require a bit of work from you, but if you perservere you can bring them through and develope a strong viable colony by late fall. Another personal preference for me is hivetop feeders, enables you to feed in volume, and practically immune to robbers as they would have to make their way through the entire colony, another idea get pollen substitutes to stimulate brood rearing , assuming that your area at the time has little food sources available for the bees. Just food for thought.