Annoying invasion

Immigrant bugs attack Styrian oak trees

Viewed under a microscope, the mini bugs are bizarrely beautiful, but they can be dangerous for oak trees.(Bild: Krone KREATIV/Adobe Stock, BFW/Gernot Hoch)

The North American oak mealybug has spread explosively in Styria this year. For humans it is "only" a nuisance, but for trees it can become a long-term threat. 

If you are out and about in Styrian forests these days, you can see in many places that oak leaves are already changing color and some of the trees are shedding immature acorns. This early start to the fall can have a variety of causes, but experts also see a new factor for Styria: "This year we are seeing a massive occurrence of the so-called oak net bug, an insect introduced from America," explains Martin Krondorfer, Head of the Pichl Forestry Training Center in Mürztal.