Hummingbirds often "disappear" from feeders during early and mid-summer as they are busy raising their babies. Young birds eat a diet of protein in order to grow quickly, and birds (even hummingbirds) mainly use insects to provide this. As the babies fledge, they will start to utilize the feeders (as well as their tired parents) in order to fatten-up for their fall southern migration.

You can keep the feeders up as long as you like - using them late in the season will not hamper their migration instinct, but it will help feed lost or late birds as they continue south. Keep the feeder solution fresh as always, though you could use less of it for now to minimize waste until you see visitation pick back up again. Males will probably appear first, as they start migrating first. In fact, birds visiting in late summer and autumn will actually be migrants who have already started their southward journey from states north of us.

If this absence is more noticeable than it was in prior years, perhaps there are more breeding females (as opposed to unsuccessful breeders) and fewer males in the area than there were in prior years. Plus, the uncommonly cold weather that lasted later into spring than usual may have delayed the start of their breeding efforts.

Here is more information if you are interested:
http://www.hummingbirds.net/migration.html

https://www.allaboutbirds.org/news/youre-seeing-fewer-hummingbirds-at-your-feeder-should-you-worry/

Miri

thank you  -that's reassuring.