Harmonia axyridis. Or In other words, this little critter:
The Asian Ladybug Beetle is a non-native species that was introduced in many parts of the world to combat pest species such as aphids. However, it has become a nuisance of its own right, as is so often the end result of such well intentioned exotic introductions.
Being larger and more aggressive than native ladybugs the Asian Ladybug has started to dominate and replace native species in parts of Europe. And, like most beetles in its family it uses isopropyl methoxy pyrazine, a foul smelling chemical, as a defensive chemical against predation. What sets the Asian Ladybug apart is due to it higher concentration of isopropyl methoxy pyrazine than in native beetles, and its ability to release a foul smell when disturbed, which has deterred normal predation from birds, resulting in a population explosion of this species. I see them everywhere during the summer.
The combination of their sheer numbers and foul smell is what can result in horror for a winemaker. In wine, it is called “ladybug taint“. And it can ruin an entire batch of wine.
Unfortunately, as it does not take that many Asian Ladybugs to taint a batch of wine, especially smaller batches like we produce, preventing Asian Ladybugs from entering the crusher and press is now an added burden that must be dealt with by many winemakers. Pheromone traps can help remove some from the vineyard, but they are not necessarily fully effective, so we employ a multi-process solution during harvest:
- Visually check each cluster as it is picked. The cluster is examined for Asian Ladybugs and any seen are blown off (using your fingers to remove them may result in them releasing a foul smelling chemical burst).
- Smell the grape cluster. I know this probably looks weird to a passer by, people “sniffing” grapes, but any clusters with a foul smell (maybe as high as 1%) are discarded.
- For tight cluster wine varieties (which are most of the varieties we grow), many small critters can hide between grapes and withing the cluster (1). So the grapes are allowed to rest several hours in the cool cellar. The harvesting process agitates any inhabitants which then seek an escape. It is not uncommon to find many Asian Ladybirds at the rim of the container after that period, at which point they are brushed off into a bucket of water (to prevent them from crawling out and contaminating the processing area or flying into the press or crusher nearby).
All these extra tasks are tedious, and they add to the total labor in wine making. But then again, making something fine and of high quality is never really an easy task.
(1) Footnote: Few wineries will admit it but many, even the most expensive high brow labels, likely end up having some very tiny fraction of swished bug juice in the primary fermentation vat — it is usually unavoidable except, for example, by those making wine from individually selected berries off clusters, or anything similar with a highly selective preprocessing process.
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