OtherPix: 17: Mating
This photograph was made at the same site in August 2014 and this time the roles have been reversed; now the male is a Migrant Spreadwing (Lestes barbarus) and the female is a female Robust Spreadwing (L. dryas). If you think of the male's appendages and the female's pronotum as a lock-and-key system, then this photograph clearly shows he's made a mistake: this lock and this key don't match. After a few minutes the male realized his mistake and the tandem broke up.
For a detailed view of a male Lestes dryas in tandem with a female L. barbarus which more clearly illustrates the mismatch between her pronotum (the lock) and his appendages (the key), hover your mouse pointer here.