The utility model discloses a foldable firefly adult collecting device which comprises a box cover and a box body with side walls being gauze, wherein the box cover is movably connected with the box body to form a push-pull box cover, the box body includes two inclinedly arranged supporting frames, and the two supporting frames are symmetrically disposed in the box body. One end of each supporting frame is fixed on the top of the box body when the box body is assembled and the other end of each supporting frame is fixed at the bottom of the box body. When the box body is folded, the supporting frames are separated from the bottom of the box body, the connecting points of the supporting frames and the top of the box body form pivoting points, and the supporting frames are parallel to the bottom of the box body after the box body is folded. The foldable firefly adult collecting device is simple in structure, convenient to carry and low in cost. The foldable firefly adult collecting device can be quickly assembled when used and rapidly folded after being used, and can prevent firefly adults from escaping from the device.