Designed for the 15 metre racing class, the Mosquito replaced the Libelle in Glasflügel's production line. It married the Standard Class Hornet fuselage with a new flapped wing employing the ubiquitous FX 67-K-150 airfoil. The wing featured innovative interconnected trailing edge dive brakes-variable camber flaps. The glider had automatic connection for all controls: ailerons, elevator, air brakes and water ballast.
The maiden flight of the Mosquito took place in 1976. It is by all accounts a nice-handling, comfortable and pleasing aircraft, but a little less performing than the contemporaneous Rolladen-Schneider LS3 and ASW 20. Therefore, the Mosquito (and the Schempp-Hirth Mini-Nimbus that shares the same wing) did not do well in top level competition, neither did it find the large commercial success of the Libelle. The Mosquito was superseded in 1980 by the Glasflügel 304.
The 303 Mosquito is often referred to as the H303 or H-303. This is incorrect, as the H designates gliders designed for Glasflügel by the Hütter brothers.