Egg laying in fruit flies can be triggered (induced) when males deposit their sperm in the spermathecae of the females. what is the selective advantage of induced egg laying for the male flies?

The advantage of the induced egg laying is that the sperm male flies is normally used for fertilization.

Fruit flies usually lay egg near the surface of fermenting foods or organic materials an dthey there eggs under the lid and the tiny larvea enter the container upon hatching. Thus, the tiny larvea feed near the surface of the fermenting mass and the advantage of the induced egg laying is that the sperm male flies is normally used for fertilization.