Garden slugs are likely to blame for the large, irregular holes in the leaves of my Hostas along with many of my other landscape bushes. My research shows that slug traps (beer traps) are effective for trapping the slugs. In addition to finding slugs in the traps each morning, I also confirmed the nighttime activity using an infrared trail camera on time lapse.
The first three nights, using four traps, yielded about 45 slugs caught. The fourth day yielded about a dozen more. Most likely this is too little, too late for this season to save my Hostas. I will be sure to dispatch slug control measures earlier next year.