The papaya fruit fly has been a huge problem lately and is infesting about 75 percent or more of my papayas. It is almost not worth it to grow papayas if such loses are normal and cannot be controlled. I try bagging and the fruit still occasionally gets infested. Bagging can be successful and it is very important if you want success growing papaya but you must bag right after the petals fall off. This is the one of the worst pests and you people in California and elsewhere are very fortunate it is only found in south Florida.
The first year not many papayas were infested but this year it is really severe. When I find an infested fruit I cut it in half and then place it in a bucket of water. Papaya is easy to grow unless you grow it where the papaya fruit fly pest is present then it becomes an extremely high maintenance hobby. I am having a lot more success with growing bananas, avocados, and mango. I still harvest a few papayas but most get infested with fruit fly larvae.