Fig. 3. Smoke wire visualisation of tethered Manduca sexta with the plane of the undisturbed smokestreams coincident with the thorax, close to the centreline. Flow is attached for the majority of the downstroke but separates at the end of the downstroke (images C-E); the separation has the same size and form as that containing an LEV in Fig. 2, and in previously published flow visualisations of outboard positions along the wing (Willmott et al., 1997; Ellington et al., 1996). The centreline position has not previously been analysed by flow visualisation.