(A) Scanning electron micrograph of the ovipositor of D. suzukii showing bristles on each vaginal plate (VP). White arrowheads = thorn bristles type 1. White arrows and black arrowheads = thorn bristles type 2. (B) The distal part of the ovipositor of D. suzukii showing trichoid sensillum (TS), long bristle (LB), and thorn bristle type 1 (TB1). Extended description: Three TS are at the distal end of each VP (B). Each is inserted in a basal socket, is ~10 μm in length, and tapers to a fine tip. One LB, ~25 μm in length, is at the distal end of each VP (B). Each LB has a large socket and a smooth, slender, curved shaft that ends in a fine tip. TB1 are stout, blunt-tipped bristles ~14 μm in length (white arrowheads in A). There are 12–14 TB1 in a row, close to the distal lower margin of each vaginal plate. They have a longitudinally grooved shaft inserted in a narrow socket. This type of bristle has no counterpart in D. melanogaster, and could conceivably function in evaluation of the stiffness of oviposition sites; D. suzukii differs from related species in its preference for substrate stiffness. TB2 are similar to TB1 but are less stout, have wider sockets, and are located in two groups. The first group is a row of four bristles of variable size (A, white arrows), located on the upper margin of the distal half of each vaginal plate. The second group consists of 10–15 bristles (A, black arrowheads) in variable locations on the proximal half of each vaginal plate. In D. melanogaster, this type of bristle is represented only by a row of 10–15 bristles along the length of each vaginal plate (Hodgkin and Bryant, 1978; Lauge, 1982).