This is a tricky one. We understand there isn’t a specific solution yet for the guava moth.
What seems to work is having a lot of beneficial insects around the trees. Plant herbs and flowers that attract beneficial predators near the trees – things like borage, alyssum, hyssop, sage, lavender, and echinacea.
If you spot guava moth this season, you could try spraying a mix of neem oil and water all over your fruit trees including the fruit. It works best when sprayed on developing fruit.
And if you do get an infestation, then infected fruit should be removed. Don’t put them in your compost, as this will allow them to continue breeding on your property.
Finally, keep your trees in good health as healthy trees are usually less likely to be attacked.