Wormy cherries: what caused it and how can I save this year’s crop?

Q: Why did my cherries rot with little worms last year and what can I do to save them this year?

A: Spotted wing drosophila, a tiny fruit fly native to east Asia, is now widespread in Britain.

It lays its eggs on ripening fruits of all sorts, including wild blackberries, ornamental pyracantha and ripe apples. In practice, in gardens, it is usually cherries that are spoiled. Other fruit flies are harmless, feeding on rotting vegetation.

The simplest, if laborious, protective measure is to make or buy sleeves of garden fleece to cover fruiting shoots, which also prevents losses to birds.

For economy, you can also use plastic bags such as those in which bread is supplied, making a snip at the base to let rain drain away – this works well.

In theory, you can make vinegar traps and reduce pressure by disposing of all and any rotting fruit all summer and autumn, but realistically this could harm helpful creatures and your neighbours would have to be equally scrupulous for a worthwhile effect.