Possible lantern fly sighting.
I think that I saw one in our backyard garden, also suspiciously in the vicinity of our black walnut tree. I did not know about the existence of this invasive species at the time I noticed it, a couple of weeks ago—I simply thought 'That is a really strange looking insect with that fire-engine red component of its anatomy.' But by pure coincidence, I am a magazine editor and we had assigned an article on the lantern fly invasion. The text arrived a few days ago, and I googled for images of the lantern fly. There it was! To my horror. The strange insect I had spotted. Is is possible that one could get lures and traps, especially to try and protect the black walnut? (I now know from editing the article that lantern fly will attack and destroy countless species of trees and plants, not only its preferred black walnut and Tree of Heaven.) I have a totally organic backyard flower, shrub and vine garden, never sprayed, numerous numerous native plants, pollinator, butterfly and bird refuge, so I don't want to use pesticides. But because I am in DC (the neighborhood of Chevy Chase, DC, contiguous with Chevy Chase, MD,), it did not seem to me that DC has an Extension Service to contact. Hoping that you may be able to offer advice, in case I did see a lantern fly—almost certain now, looking at images, that I did.
District of Columbia County District of Columbia
We realize your sighting was a couple of weeks ago, but a photograph would be immeasurably helpful in identifying the insect you saw. Can you monitor your landscape for additional sightings and please submit photos if you find another suspect insect? If a juvenile, it may be not far from where it was seen the first time; adults can fly of course, and so may have left the area. Both life stages can be present in July, at least in PA. In the meantime, we are checking into what agency you should report it to in case a future ID is positive.
You may have already read this, but in case not, here is our page on SLF with several associated links for more information: https://extension.umd.edu/hgic/topics/spotted-lanternfly