What 螿 means
It names a small, blue-red cicada associated with the cold season.
The earliest known written reference appears in the Huainanzi, a Chinese text compiled in the Western Han around the second century BCE.
A commentary on the Erya, an early Chinese dictionary, links 螿 with 寒蜩, another name for a cicada. Later dictionaries and poetry use 寒螿 for the insect's autumn call. 螀 is its simplified Chinese counterpart.
Literary and old-fashioned; expect it in classical writing rather than everyday chat.
Sent alone, it gives no reliable clue to the sender's intent.
Questions people ask
1Why does 螿 show as a square?
The font being used may lack a glyph for 螿. A font that includes this Chinese character can display it; the missing-glyph box is not another character.
How to type 螿
螿\87BFCodes and encoding1 code points
A visible symbol can contain several code points. JS .length counts UTF-16 units; UTF-8 counts bytes.