Question My mango tree is about two-storeys high. The tree fruited twice but on both occasions, the mangoes had black spots on the flesh and worms were present. Can you please advise how I can eradicate the worms so that I can enjoy the mangoes? Thank you. – W.F. Chow I have a mango tree almost two storey in height. During the recent dry spell, it flowered profusely. When the small fruits appeared, I sprayed it with a water-based permethrin solution. Despite spraying three times over a period of three weeks, the fruits had worms inside. How can I overcome this problem? – W.L. EngAnswer Female fruit flies lay their eggs just beneath the skin of the developing fruit. Spraying the fruits with water-based permethrin solution would generally not be effective, as the pesticide is a contact insecticide, meaning it needs to be sprayed directly on the insects in order to kill them. The most environmentally friendly way of dealing with this problem is to protect the fruits from being infested. This would involve covering the fruits with fine netting or newspaper. However, this of course requires that it can be done safely and would be easier accomplished if the plant is a dwarf or of a small-growing variety. You could refer to this webpage and scroll to the section on making a fruit fly trap (Lynfield or bucket trap). You can replace the vinegar used in the webpage’s suggested ingredients with fruit fly attracting solution available at major nurseries. Some people drop insecticide such as malathion into the solution to poison the fruit flies. You will often find that a variety of management methods have to be applied rather than just one solution in order to better control pest infestations. – Dr Wilson WongPhoto of mango tree from NParks Flora and Fauna WebAsk the Expert team is made up of NParks horticultural and gardening experts. If you have any questions on plants or plant-related subjects, please send your question to Ask the Experts at nparks_communications@nparks.gov.sg