Kill them all

And let God sort out the rest.

You have to either maintain regular control or grow only plants they do not attack.

I live in the Cascade foothills in the Columbia River Gorge, and have killed upwards of 500 large slugs in the yard portion of the property this year, and have not had anywhere near that number for several years previous. And that's just the "morning murders" as my husband calls them. I haven't ventured out at night yet, but I'm seeing a lot more slugs out and about this year.

Have you brought in topsoil, mulch, plants, anything like that?

Also, you might want to check out the life cycle of a slug - they have lots of babies! I had to pick off many dozens of bitty slugs from my echinacea a few weeks back. (I didn't count those in my death toll!)

Best of luck. The most effective way to really make a dent is to go out at night with a bucket of soapy water and a pair of nitrile gloves. Pick and drop, pick and drop. YOu'll be amazed.

The slug baits are for the most part very eco-unfriendly, so beware. Many kill pets. I have one bait that I resort to in some areas, it's pet-safe and only gets eaten by slugs and snails, but it's not a cure-all.

If you are buying new plants from nurseries then you are importing the brown snail that is overrunning California and laying eggs in nursery plants. Check your plants over carefully when planting, for tiny baby snails, and look for their eggs in the soil - little pale plastic-looking spheres in clumps in the soil, that you should smash immediately.

How many do you have to kill? All of them.

And next year start early before they start reproducing. I begin putting out Iron based slug bait when the bulbs come up. That's usually February.