Sparse winged-humanoid reports surfaced in the Chicago area around 2011, then largely quieted. In early 2017 a much denser wave began. Lon Strickler’s Phantoms & Monsters site and related fortean collectors became the main intake: by mid-to-late 2017 they had compiled on the order of fifty-plus Chicagoland reports (counts vary by who is tallying). Local outlets — including the Chicago Tribune, Vice, and later WBEZ Curious City — covered the flap as a city story, half cryptid news and half cultural meme.

Descriptions vary. Common threads: a large flying figure (often estimated several feet tall with a wide wingspan), dark coloration, bat-like or bird-like wings, sometimes humanoid limbs, occasionally glowing red, orange, yellow, or green eyes, and rare reports of screams or close approaches. Many sightings were brief and at distance; some witnesses first thought “huge bird” or “odd aircraft.” Locations clustered in the city and suburbs, frequently near Lake Michigan, harbors, parks, and rivers — Northerly Island / Burnham Harbor, Adler Planetarium area, Calumet parks, neighborhood streets, and at least one widely retold claim of a figure on a building roof that flew when lights hit it. An August 2017 Northerly Island report during eclipse viewing described a loud brake-like scream and a large black bat-like object with arms and legs over the docks.

The nickname “Chicago Mothman” (earlier sometimes “Chicago Phantom”) came from online and press comparison to Point Pleasant, not from a demonstrated biological or historical continuity. Strickler published Mothman Dynasty: Chicago’s Winged Humanoids (2017) collecting accounts. Sightings continued more sporadically into later 2010s and early 2020s around the Lake Michigan basin (including claimed encounters near O’Hare / Rosemont), but 2017 remains the peak year in public discussion.