1.   Male flies have acute vision to stalk a potential mate to whom her suitor is a distant blur.

2.   But flies may have another, more compelling reason to keep their feet clean.

3.   Flies have a daily rhythm.

4.   For instance, flies have receptors for sugar in their feet, or tarsi.

5.   In fact, the gene sets more of a framework than a rigid program, since the fly has some flexibility in its routine.

6.   The hookless fly has no large bend and point hanging down beneath the body of the fly, adding weight to what in nature is nearly a weightless creature.

7.   The fly has many virtues.

8.   These flies had the inserted genetic fragment, but the fragments were nowhere near the gene that the scientists were studying.

9.   Those flies also have more trouble finding serrata mates when raised along with birchii flies.