At first, fruit flies eat like horses. Hatching inside over-ripe fruit where they were laid, they feed wildly in the sugar-rich environment until nature sends them an offer they can't refuse.

To survive, they must leave the fruit, wander off and burrow into the earth where they avoid food as if it were poison.

Only then can the larvae grow and hatch into flies that will take wing to lay their own eggs. Researchers have now discovered that the important...