What word does your mother always say?
1947, from litter + bug (n.). According to Mario Pei ("The Story of Language," Lippincott, 1949) "coined by the New York subways on the analogy of 'jitterbug' ...."
A person who throws trash in the streets, parks, etc
[1947+; coined for a New York Police Department campaign against littering; modeled on jitterbug]