Apples Spark Evolution in Insects Apples seem like one of the most common, ordinary fruits we come across in this world. They've been around for centuries, and even have their own motto: "an apple a day keeps the doctor away." But this seemingly ordinary fruit sparked the evolution of countless insects. Before apples were introduced to the United States only one species of fruit fly existed, which fed off the fruit of Hawthorn trees. With the introduction of the apple, a new species of fruit fly emerged to feed off apples. The evolution of this one fruit fly then had a domino effect of bringing about the evolution of many other predatory insects. The appearance of one new species creates a niche opportunity for other species to evolve and new species to form. In this case, the parasitic wasp took advantage of this new species of fruit fly to create new species of wasps. For example just three of the known predatory species of parasitic wasps that feed on these fruit flies are in the process of diverging into two more distinct new species. Who knew one fruit could have that kind of explosive effect on the insect world? Did you know the powerful change apples brought with them when they were brought to the U.S.?