Slugs and snails can be a problem, turning your hosta leaves into swiss cheese in no time.  While they do no long term damage to your hosta, I recommend a slug product called Sluggo because it uses Iron Phosphate and can be used safely around cats and other outdoor animals.  Once the slugs take in Sluggo they no longer feed and expire. 

 

Sluggo recommends applying it when the soil is moist.  I walk around with a watering can and Sluggo and look for hosta that show slug damage (small to medium size holes in the leaves), apply a little water around the hosta and put a few pellets around the plant.   I use the product when I first start to see damage.  I walk the gardens once or twice a week and apply selectively.  I also tend to learn which hosta the slugs go after and check them or apply proactively.