Switzerland loves roasted chestnuts, particularly in the winter months. But the supply has been dwindling in recent years, and an Asian wasp is reportedly to blame.
According to The Local, Swiss people eat nearly 2,000 tons of chestnuts a year. The chestnuts are usually eaten in sweet desserts or just roasted and eaten out of paper cones on the street, but in recent years the chestnut harvest has seen quality and supply problems because of an infestation of Asian wasps that came up from Italy.
Gall wasps attack chestnut trees, but do not kill them. The weakened trees thus produce smaller quantities of chestnuts, and the ones they produce are not generally as robust as those produced by healthy trees. As a result, chestnut harvests have dropped dramatically. In one canton, the harvest has reportedly fallen from 120,000 pounds in 2006 to just around 220 pounds this year.
Switzerland is still trying to figure out how to deal with the gall wasp problem. One potential “swallow the spider to catch the fly” solution is to bring in another kind of Asian wasp to attack the gall wasps. It is not actually legal at the moment to import the new wasps into Switzerland, but officials say the new wasps seem to be following the gall wasps up from Italy, so the problem might soon start to fix itself.