Most pesticides will kill them, and they are easy to catch and smash. They also die easily when heat or frost arrives. The most aggressive and effective way to stop their spread is to remove one of their favorite food sources: the tree of heaven, which is also an invasive plant, Professor Urban said.
The lanternflies’ best defense is in their ability to reproduce. They breed in huge numbers, laying 30 to 50 eggs at a time. Their eggs, which can be laid virtually anywhere, including on trees, trucks and the tops of railroad cars, take eight months to hatch, Professor Urban said.
“That gives them time to be transported via humans’ travel,” she said.
Despite its name, the lanternfly is a planthopper, not a fly. It first appeared in the United States in September 2014, most likely from China, Professor Urban said.
The insects were spotted on imported stone at a landscape supply center in Berks County, Pa., she added.
Since then, lanternflies have spread across the northeastern United States. In Delaware, the state Department of Agriculture is monitoring and trying to eradicate five satellite populations, said Stacey Hofmann, a spokeswoman for the agency. Reports of sightings keep coming from two counties, and the state is worried that a third may have become infested.
“People may not realize that the insect has fallen into the bed of their truck, hopped into their car or is on an R.V. or boat,” Ms. Hofmann said.
In New Jersey, eight counties have been designated “quarantine zones,” which means in part that residents should inspect their vehicles before they travel. In Pennsylvania, where there have been 18,000 reported sightings of the lanternfly, 34 counties are under similar restrictions.