Winemaker Notes: Ladybugs: Friend or Foe?

The ladybug was first introduced to North America during 1916 from Asia (Japan and Korea). They are actively sold and marketed as a form of bio-control against aphids and some small soft-bodied pests. One can purchase thousands of them for this purpose. While it has proven very efficient in certain pest control, MALB (multi-coloured Asian Lady Beetle) adults can accompany the fruit on the harvester and subsequently be transported on fruit to the winery; this is not an ideal situation. Unfortunately, if ladybugs are present during winemaking operations, they can produce off-aromas and flavours in the wine known as ladybug taint (LBT). Chemically, the taint is produced by an order of compounds defined as methoxy-pyrazines, which isn’t of interest to most people, but winemakers tend to be fussy about it!

Whilst Bee & Thistle Orchards encourages the proliferation of ladybugs to control aphids (particularly on Black Currants and garden vegetables), we conscientiously sort wine-destined fruit at the conveyor belt and washing stations; we don’t kill them, but return them to the gardens as much as possible. Generally speaking, we do not see more than one or two ladybugs per 100 pounds of fruit, and they are easy to spot and sort out. So, yes, ladybugs are both friend and foe. It depends on what you growing or making. But we won’t be purchasing any for deliberate pest control anytime soon.

Harmonia axyridis, the common ladybug or Multi-Coloured Asian Lady Beetle (MALB)