Sentence:  Crickets are a <WSD>mainstay</WSD> of panfishing with live bait—and a <WSD>mainstay</WSD> of bait shops—but they come off the hook easily and you'll be plagued by minnows and tiny fish constantly stealing your bait. 
Meaning of the word marked with <WSD> tags:  Someone or something that can be depended on to make a regular contribution.