In 2014, employees with the Pennsylvania Department of Agriculture reported unfamiliar insects around trees in Berks County. Investigators identified the bugs as spotted lanternflies and found them at four sites, including a business that imports landscaping stone from China. Agency officials suspect that the insects first arrived a few years earlier as egg masses, which resemble smears of mud, stuck to shipments of stone (see A Bug’s Life Cycle).
Spotted lanternflies don’t bite or sting and don’t pose any direct threat to people. The trouble with these pretty pests is their feeding habits. Adult lanternflies and juvenile nymphs pierce plant tissue to suck up sugary sap—the plant’s food supply. The insects feed on more than 100 plant species and prefer some of the most economically important ones in the U.S., such as apple, maple, peach, pine, oak, and walnut trees, as well as grapevines.
By stealing energy and nutrients, lanternflies can kill vines or young trees. Mature trees may be left damaged and weakened, vulnerable to other pests or infections. As the insects feed, they also excrete a sticky fluid called honeydew. The sugar and moisture in honeydew often lead to mold growth that can weaken trees, kill delicate plants and vines, and spoil fruit.