The present invention relates to a fly baby comprising, in a tubular body 2, a chamber for retaining the mucus and a chamber b of the expansion of the suction flow, the chamber a which includes means 7 for supporting and longitudinal positioning of a buffer - filter 8 in the open cell foam, and an axial protrusion 10 thus contributing to the retention of the mucus. It has for its object to organize the distribution of the mucus in order to ensure that it does not clog up the buffer and makes it necessary to increase the suction power. To this end, in the chamber a, the distance l between the support means 7 of the buffer 8 and the end 11 of the protuberance 10, is less than the thickness e of the cover at rest, so that, after assembly, the central part of this buffer is compressed by the axial protrusion 10, with the effect of shifting the passage of the suction flow in a peripheral crown w.
