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Fig. 1. Location and size of spiracle openings in the fruit fly Drosophila
melanogaster. (A) sp1, mesothoracic spiracle; sp2,
metathoracic spiracle; sp39, abdominal spiracles. (B) Scanning
electron microscopic image of Drosophila shows the position of the
anterior spiracle sp1 between propleura and mesopleura. The posterior
spiracle sp2 is located between the basis of the haltere and the
mesomera. In Drosophila the prothoracic spiracle is reduced. (C,D)
Shape and size of the spiracle opening area of sp1 and sp2,
respectively. Red shading approximately indicates measured spiracle opening
area. The metathoracic spiracle opening area is approximately 26% larger than
the mesothoracic spiracle opening area. Values are means ± s.d.,
N=10 flies.