Green’s Dictionary of Slang

1. (US Und.) a night watchman.

1929		C.G. Givens ‘Chatter of Guns’ in Sat. Eve. Post 13 Apr.; list extracted in AS VI:2 (1930) 131: bugster, n. Night watchman.
1950		Goldin et al. DAUL 35/2: Bugster. A night watchman. ‘Tail (follow) the bugster on his rounds and put the slug on (overpower and bind) him when he’s through.’.

2. (US prison) a safe-breaker.

1960

(con. 1950-1960) R.A. Freeman Dict. Inmate Sl. (Walla Walla, WA) 19: Bugster – one who specializes in blowing petes.