Why are there crickets spawning in my apartment?

Did you tell a bad joke recently?

Get a cat. They will launch a pogrom not seen since WWII.

Maybe a neighbor of yours has reptiles as pets and it's their crickets that are escaping.

Maybe there's a mob spawner in the wall?

Joke aside, they either follow someone in or climb all the way in.

That's what happens when you build on the spawn block

Because a cricket laid eggs in your apartment.

Neat. Now you don't have to go out an buy crickets.

You been cursed. Get in touch with your local sorcerer.