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Diversity of bristle patterns on the fly surface.
In this adult male, the eye bristles occupy alternating vertices of ommatidia in a hexagonal lattice. The sex comb typifies a 'tandem' array where bristles touch. Other leg bristles are aligned in straight ('regular') rows but spaced evenly. On the notum the rows tend to be irregular, especially laterally. The four scutellar macrochaetes form an aperiodic ('constellation') pattern that is constant from one fly to the next, as are the arrangements of other macrochaetes. Most tergite bristles (except those at the posterior edges) are arranged randomly ('isotropically') but spaced uniformly. Tergite pigmentation has been omitted for clarity. Adults are ~3 mm long . Adapted from .
For anatomical nomenclature, see . See also App. 7.
What sort of geometry does the fly skin use to create these patterns? Do the diverse arrays arise via the same basic algorithm? Do bristles know where they are? Are bristles at separate sites nonequivalent? The mysteries of this 'golden fleece' have intrigued investigators for decades [1799, 1804, 1808, 2434, 4096].