This term is a good synonym for 'miscreants'--and exclusively young ones.

The 'deil' part (also: 'deel') is 'devil'--in the way we might think of a young one as a 'little devil' (rascal).

The 'buckie' part is more interesting. A buckie is apparently another term for a whelk, which is in the Buccinidae family of sea snails.

Sir Walter Scott used the term. Is it a term in Scotland still?