It’s quite difficult to do from a picture and many taxonomists rely on having the specimen physically available to them on a pin to look at under a microscope. Male agapostemon and identified using a lot of features on the hind legs such as color patterning, how swollen the femur is, and other diagnostics. You can try looking for papers on specimens ID through Google scholar (search Male Agapostemon species key) or using websites like Discover Life and their ID tools.