Yes, it's true.
The ripening of fruits is controlled by phytohormones produced by the plant itself. However, the larvae of insects developing inside the fruits are interested in the fruit ripening faster: the soft and sweet pulp is more nutritious and easier to digest.
Therefore, the larvae also secrete phytohormones or their analogs that slow down the growth of the fruit and initiate the ripening process. Wormy fruits usually exhibit all the signs of ripeness, but they are typically much smaller than healthy fruits and often have irregular shapes.
