Could be a backswimmer or boatman bug. I forget which name goes with which bug, but one of them eats algae, and the other eats the other bug. To have a bunch of either could be a sign of the start of an algae bloom. I'd do an OCLT to check for algae. You could also raise you pool to SLAM level for a day or two to kill off any algae in your pool, then do an OCLT to make sure you don't lose chlorine overnight to algae.
Those bugs wouldn't be in your pool unless there's a food supply for them there, so take that as a warning.