Vermin around my livestock

[Zottel]

Hi, I took pigs at the start of the game and since the start I have had worms, slugs and bugs and all that stuff around them non-stop. I also have 3 cats roaming around the fortress and the vermin don't spread to the stockpiles (at least not visibly) but I'm still worried about the consequences. What can happen if I don't act or do I have to get rid of them (and how?) or are they harmless as long as they just stay around the pigs?

[Johan 2.0]

You can set up a pasture and stick a cat in it on top of your food stockpile. Most vermin are harmless, dwarves can eat them if there is nothing else and some vermin can be milked or extracted. You will never get rid of all the vermin unless you take measures to ensure harvests are dealt with and food is all tucked away in a timely and efficient manner. I'm pretty sure worms and the like are dug up during grazing of animals or its the birds scratching at the grass.

[Sayla Massochist]

Some animals that can graze on stone (various birds, pigs, etc) will graze on snails and slugs and worms and such. You'll see them pop up as the animals dig around on the stone floor. More or less then are harmless. Keeping a couple cats about will prevent anything to bad going on in your actual stocks and if worse comes to worse your Dwarf kids will chase vermin and might eat them as well.

[Johan 2.0]

Originally posted by Sayla Massochist:

Dwarf kids will chase vermin and might eat them as well.

Sounds like a viable alternative to feeding them is to lock them in the pig pasture.

[Zottel]

Well, it can't be grass and pasture because I dug a room underground for the pigs and the vermin literally moved there with them. But if you say that the pigs also dig around in the rocks and thus attract the vermin, that can of course also be possible. In any case, there are no bugs on the pack animals that I have left outside. So is it enough to put the cats in the storage areas? Is it actually more effective to have more cats or does it not make any difference after a certain number?

[Johan 2.0]

I have 4 cats and they all free roam, creating an issue with vermin corpses rivalling the mussel shell epidemic. One should be enough for a decent sized area and they tend to run off and hunt actively so you shouldn't waste time herding 30 cats.