Bug flew into my door, I thought it was a robber

[Clair de Lune]

Cicada. A harmless creature. It lives underground for 7-12 years(!) as a nymph eating tree roots, then it emerges up the tree to shed off its skin and get wings. It sucks on tree sap and sings throughout the summer, mates then dies. The winged stage only gets to live for mere few months.

 

[Ruptga]

Originally posted by: Chronoshock
Cicada?

yup, quick way to confirm is to go outside. If you're deafened by buzzing and/or find a bunch of these on trees/walls/posts/brick walls, it's definitely a cicada