Many of these tiny "split-horn" sawflies flitting around my vegetable garden. Common Purslane (Portulaca oleracea) is a weed in my vege garden which may be attracting them. I believe the larvae feed in the inside of the purslane leaves. I think only the males have the split/bifid antennae, so the photos would be of a male. (The photos may not all be of the one individual).