This is in the current (Winter 2013/14) issue of Johns Hopkins magazine for an article on the art of translation. I had no idea that Kafka didn't write anything about "cockroach" or "insect" -- he used a word more akin to "vermin". (When I read it, I got the distinct impression of cockroach.) From Wikipedia:
English translators have often sought to render the word Ungeziefer as "insect", but this is not strictly accurate. ...Ungeziefer literally means "unclean animal not suitable for sacrifice".
p.s. this one is NOT in the stock shop :)
p.p.s. "unclean animal not suitable for sacrifice" is my new insult of choice