They're sort of friendly. But kill them immediately.

A spotted lanternfly adult and nymphs. (Photo by Stephen Ausmus, USDA)

The spotted lanternfly (Lycorma delicatula) is an invasive insect from China that was discovered in Pennsylvania in 2014. "The spotted lanternfly remains a problem in Pennsylvania and has become a growing concern in neighboring states as the invasive leafhopper migrates, and hitchhikes, south (noted here)," reports Dan Sullivan of Lancaster Farming. "Efforts by entomologists, extension agents, farmers and the general public to stay ahead of the curve through studying the insects' behavior have yielded some surprises."

Sullivan provides some expert spotted lanternfly knowledge and tips:

• They don’t bite people; they’re actually kind of friendly, according to one extension agent (but they do cause damage and present a nuisance, so don’t go adopting one for a pet; in fact, it is widely recommended that they be dispatched upon sight).
• They’re not killing landscape trees, but they will kill tree of heaven (Ailanthus altissima), a rapidly growing deciduous tree native to East Asia and a widespread invasive species across North America that is the spotted lanternfly’s favorite host plant.
• They damage grapevines by sucking out nutrients, thus reducing the plant’s ability to make energy through photosynthesis and starving it of the starch typically stored in roots for survival through winter.
• While they have not been shown to kill or damage stone fruit or nursery stock, they have presented additional tasks for commercial nurseries due to the inspections required to ensure that plants are free of spotted lanternfly before they are shipped.
• Contrary to initial alarm bells indicating they were impervious to controls, insecticides, including “softer” insecticides such as insecticidal soap, have been shown to be effective in dispatching spotted lanternfly.
• Their population numbers fluctuate from year to year.
• Beneficial predators — such as praying mantises, spiders, wheel bugs and birds — offer a biological control.
• Certain naturally occurring beneficial fungi, such as Beauveria bassiana, offer another biological control, especially in rainy seasons.
• For now, Pennsylvania regulatory measures will remain in place, e.g., businesses and agencies, especially those that transport materials, are required to obtain a permit indicating employees have been trained on identification and removal, and that items have been inspected to remove spotted lanternfly.
• Individuals may still assist in spotted lanternfly control and are asked to do so by inspecting items, especially those that have been stored outside, before moving them and to destroy any egg masses and spotted lanternfly nymphs or adults upon discovery