When I spotted this possible wasp working the Jewelweed leaves by the Assekonk Swamp, I realized, fairly fast, that it was actually a fly doing a fine job of mimicking a hymenopteran. But when I started to try to determine precisely which kind of dipteran it might be, I ran into trouble. My initial guess, of course, was to figure that it had to be a member of the Syrphidae, the Flower Fly family of great wasp and bee mimics. But an hour, however pleasant and time-wasting—I really had other things to do—spent mining my keys and Internet resources for an identification didn't get me very close to taxonomic Nirvana, and I was beginning to despair of ever figuring this one out. Then, however, I got lucky and discovered that I was looking in the wrong place. It wasn't a Flower Fly after all, but, rather, a member of the Conopidae, a.k.a., the Thick-headed Flies. The weird antennae offered the proper clue, and before long, I landed in the genus Physocephala, where species tibialis looked just about right. Sometimes being thick-headed has its rewards... well, natural history rewards.