Tapered Drone Fly Eristalis pertinax
Two very common species are especially troublesome: Eristalis pertinax, the real Drone Fly and Eristalis pertinax, the Tapered Drone Fly. Both are rather big Drone Flies, the other species usually are smaller. The difference between the two species is the last part of the leg, just above the foot: in Eristalis pertinax it is always black and in Eristalis pertinax it is always yellow. Also Eristalis pertinax has two dark lines in the eyes. These actually are streaks of hair. When in the field you do need the right light to be able to see them, though.
