True flies (Muscidae) belong to the order Diptera, a name meaning “two wings.” Unlike most insects that rely on four wings, true flies have just two for flight. Over millennia, their hindwings have evolved into tiny, knob-like structures called halteres. These act as sophisticated biological gyroscopes, allowing flies to pull off their trademark, gravity-defying aerial acrobatics. A great example of this agility is Phaonia valida, a medium-sized (1 cm) true fly commonly found near broadleaf woodlands, where it loves to bask on sunlit tree trunks. While their larvae develop quietly in the damp forest leaf litter, the adults are active from late spring through autumn, typically buzzing around from April to November. I captured a shot of this specimen in a Swedish forest right near my home in Järfälla.