darkling beetle dark·ling·beetle uncommon noun 1. sluggish hard-bodied black terrestrial weevil whose larvae feed on e.g. decaying plant material or grain Synonymsdarkling beetledarkling groung beetletenebrionid Related words Broader terms weevil Narrower terms flour beetle Parts Tenebrionidae WordNet 2.1 (Princeton University). WordNet 2.1 Copyright Princeton University. All rights reserved.