Spotted lanternflies – beautiful but destructive pests – are already flying around in nearly 20 states, and researchers think they could set up shop in California by 2033. What would that mean for the state’s massive wine industry?
Let’s understand the situation first. California is the source of 80% of wine in the U.S., according to the Wine Institute industry organization. That’s not all: The Golden State is the fourth largest producer of wine in the world, and its wine industry generates more than 1 million jobs.
According to a Wall Street Journal report from last week, the state’s wine industry is already in “crisis” due to changing drinking habits, falling prices, tariffs, and weather. With spotted lanternflies on the horizon, as The Washington Post noted this week, a silver lining regarding the current situation might be a current oversupply of grapes.
Now to those spotted lanternflies. They are not actually flies, but invasive planthoppers native to Asia that first showed up in southeastern Pennsylvania in 2014, PennState Extension explained. Distinctive, spotted wings make the bugs easy to see, and experts have given the public free reign to squish them in an attempt to prevent their spread.
“Significant damage has been reported from SLF extensively feeding on grapevines, including reduced starch concentration in vine roots and sugar in the fruit at harvest, reduced yield in the subsequent year, and potential death of vines,” PennState Extension said.
As the spotted lanternflies feed, they ingest large quantities of sap and then release excrement called honeydew. This honeydew can be attractive to ants, wasps, bees, and other sugar-loving insects, the extension said. It can also be colonized by sooty mold fungi that can act as a barrier on the leaf and blocks photosynthesis and lead to plant death.
“Based on research data from 2018 and 2019, increasing levels of SLF on Vitis vinifera vines were correlated with a reduced number of clusters per shoot the following spring,” said the extension. Yield reductions of 80-90% have been reported in Pennsylvania from current year feeding once populations become established, per the Virginia Cooperative Extension.
In addition to grape vines, the critters like to munch on cucumber crops and hardwood trees. At many wineries, they have also been cited as a nuisance at outdoor tasting areas.
With the spread of the lanternflies, wine industries throughout North America have been on high alert. In Canada – home to Ontario’s $4.4 billion wine industry – the Invasive Species Centre is imploring people to report potential sightings. Fox reported last year that California winegrowers were on high alert for spotted lanternfly eggs. In New York state, where lanternflies put the state’s $15 billion wine industry at risk. Comparatively, California’s wine industry produces wine with a retail value of around $55 billion in one year.
Greg Loeb, a professor at the Department of Entomology at Cornell AgriTech, said in 2024 that would be only a few years until the flies were seriously impacting New York’s wine growing areas unless the pests are kept under control, according to the New York Wine & Grape Foundation. He’s been working on a project using the tree of heaven plant to lure the insects away from vineyards.
This July, Olmstead County Parks in Indiana, home of the Swiss Wine Festival, announced that it was working to remove tree of heaven plants in an effort to control the lanternfly population. Penn State Extension said another proposed method to manage the lanternflies includes treating spotted lantern fly source areas, such as an infested tree of heaven, with insecticide. In July, Audacy station KYW also reported on research regarding species of bats that eat spotted lanternflies.