An Asian ladybug with an appetite for bruised grapes has been spreading throughout the United States since 1988. Canadian researchers confirm that the foul-smelling chemicals that these bugs secrete can easily spoil an entire vintage. The researchers also describe a treatment that they're investigating for such ladybug-tainted wine.
Chemists had suspected that the ladybugs' recently identified stinky ingredients, called methoxypyrazines, were mingling with grape juice at harvest time, giving wine the taste and aroma of peanuts, bell peppers, and asparagus—a mixture unlikely to captivate oenophiles. Lesser quantities of the chemicals are also present in "green" wines made from immature fruit.
In an upcoming Vitis, researchers at Brock University in St. Catharines, Ontario, report finding that just 200 to 400 ladybugs (Harmonia axyridis) per metric ton of harvested grapes can foul a batch of wine. Depending on the bugs' methoxypyrazine output, an infestatio