Had a search but unable to locate anything specific.. These bugs swarm over the flowers and seem to eat them.Do not appear during daylight.Some say they live in the soil,but have not found any. Locals say no problem. Catch them easily and get a good price at the market lovely and crunchy.,

OK what are they? Any effective control or spray available..

Some of the flowering stems seem to have been stripped bare. Any help greatly appreciated

You have to live with stuff like this. If you spray the tree you'll be spraying half of the village at the same time and the results won't be joyful. You would need a systemic insecticide that may put you off the idea of eating your fruit. Do you have a sort of straggly, untidy looking tree, or one with a nice straight trunk?

We have three varieties of mangoes here and every year the one or the other has problems, the worst of which is rain during blossom time.

Are the insects actually eating and destroying the flowers or eating the nectar on the flowers? If they leave the flower intact after their visit, then it sounds like you should have good polination and good fruit set, that is they are beneficial. If they damage the flowers so they don't set fruit, then that is no good. You wouldn't want to spray the flowers for insects as insects are pollinators.