Where in the world did these guys come from?

I don't remember seeing these when I was growing up (I'm 50), and here in Pennsylvania it seems like they are everywhere (or at least my house). They don't seem to smell in the spring, do they before they invade my living room?<br><br>Edit: I've read through some of the comments, and understand they are native in my area, and it's just their population that has exploded in the recent years.