My grapefruits are wormy. What can I do to prevent this subsequent year? ...
Answers: There are several fruit flies which can cause this problem. In Florida Carribean Fruit flies are the most possible culprit. There are other exotic fruit flies which could cause the problem. Check near agricultural officials surrounded by your area. There may be control programs available from them. I do not know what programs Mexico have in place.
http://creatures.ifas.ufl.edu/fruit/trop...
It sounds resembling you have fruit fly, which is a big problem, depending on where on earth you live. Are they worms or maggots? (maggots are the larvae of flying insects, worms are worms - you own to find out the difference).
If the fruits have small bruises on them (sometimes beside greenish stain around a tiny puncture hole) on the peel, you must take in touch near your local council and they will come out and spray the tree.
However - I don't know where you are contained by the world. You may need to look up fruit fly on the trellis and see what advice you bring back that is relevant to your nouns.
Good luck.