UPPER MACUNGIE TWP., Pa. - Pennsylvania is the fourth largest producer of wine in the country, but there's a serious threat affecting some of the vineyards in our area.

John Landis, a partner in Vynecrest Winery, knows a thing or two about making wine. He wasn't prepared for the spotted lanternfly.

"We first saw a few lanternflies in 2016," he said.

The bugs have started posing a serious threat to vineyards. John says the bugs have cut about 10% to 15% of production at Vynecrest.

The Penn State Agricultural Extension stops by once a week to run tests on the bugs. 

"They land on susceptible plants - or plants that they like to feed on - and they damage the bark so that the sap comes out and they feed on the sap," said Edwin Winzeler, a research technologist with Penn State. 

Plants like grape vines. 

"If you spray any standard insecticide, usually that does a good job to mitigate them," Winzeler said.

However, Landis says it's still a battle. 

"It's a continuous management problem where you're going to have to spray every two or three days to keep them under control," he said.

But he's hoping for the best.

"We're having a beautiful fall, so that helps the grapes harden off and get prepared for winter."