🐝 Wasps

Wasps are insects that gnaw into sweet, ripe grape berries. Growers regard them as pests, but they also have an unexpected role: they carry yeast.

By late summer berries are rich in sugar, and wasps come for the smell. They bite the skin and drink the juice. Juice starts to leak from the damaged berries, and rot or acetic acid may get in. This is bad for the crop, especially if many berries are damaged. So growers keep watch for wasps and protect the bunches.

Scientists have found that wild yeasts live on wasps. In winter the wasps keep them in their bodies, and in spring and summer they carry them onto berries. This is how the yeasts that fermentation depends on reach the grapes. Wasps are among the pests of grapevines, and their link with wild yeast shows how nature takes part in winemaking. For a grower it is important to keep a balance: protect the crop without forgetting the insects' natural role.