What You Did
You discovered what fruit your local bugs prefer.
You should have found bugs swarming the plates of fruit. Maybe one of the plates had more or fewer bugs than the others.
If there is pesticide in your yard, or if you try this during winter, there may not be any bugs, or very few.Upset neighbors, if you live in an apartment.
This experiment can be easily conducted anytime throughout the year. When your family buys different fruits and vegetables, ask for a small piece of each one to experiment with! Just remember to record the results in your book so you can compare them over time. Critters may prefer a certain type of fruit during different times of year, and if you try in wintertime, you may not get any bugs at all since it's too cold.