Vermin....every farm has them. And you need a game plan on dealing with them, otherwise they take over.
First of all, what is vermin? In my opinion, it's an obnoxious animal that invades your farm and does harm. But I differentiate between vermin and predator, in that predators don't usually set up housekeeping on your farm. Thus I classify feral dogs, feral cats, feral pigs, mongoose, and hawks as predators. While rats, mice, flies, centipedes, and such as vermin.
Flies are a major vermin around here. There are several varieties of flies that will lay eggs on the wet wool/hair of my sheep, thus resulting in flesh eating maggots. Before I learned about flystrike, the term for this fly attack, I was problem free for two years. Then we had a wet winter and the problem appeared. I lost my ram to flystrike and had to treat several ewes. Since that first year, I have had a few cases but no deaths. Every flock owner I know has lost sheep to flystrike.
I decided to take preventative measures. Commercial flocks, plus many small flock owners around here, use pesticides on their sheep. The sheep are dipped, or a topical insecticide like permethrin is applied monthly. I opted to avoid the expense and work on some other option. What I do now works for me. I maintain fly traps to capture these flesh eating vermin, and since I've started I capture routinely four cupfulls of flies each and every day (except rain days). The flies go into the chicken food. I also shear the sheep during the warm rainy winter months, keeping their fleece short so that it is not attractive to the flies. Now I don't see flystrike.
Centipedes are vermin on my seed farm, but do not exist on the main farm. At the seed farm I noticed that centipedes like to hide under rocks and in rock piles. Thus I set up rocks specifically as centipede traps. For a few days after a rain I will check these traps and kill any centipedes found. Now these guys are not your average garden centipede. No. They are 6 inches long, orangish red, and their sting is incredibly painful. Even a minor nip will pain ya for hours. I have come up with a treatment that greatly reduces the pain, but it's best to eliminate the critters in the first place.
African snails....again, at my seed farm but thankfully not on the main farm. These snails eat any vegetation they come upon. In one night they can cause incredible damage to your crops. They survive where it is hot, feed at night, and hide someplace cool. Taking advantage of their habits, I set up traps. They will go under a two inch wet wad of newspaper to hide. Easy trap to make. When I started collecting snails I caught dozens every time I checked. Now I only find a couple. I had so many that I used them as chicken food and sold the empty shells to artists. Now I pop what I catch into a plastic bag and throw it in the freezer. Once I have a potful, I'll process them as chicken food and reserve the shells for later. Ah, waste not.
Just about every farm has mice. They live everywhere, it seems. And you never get rid of them completely because more just move in. But my aim is to keep their numbers as low as possible. Every hardware store sells mouse poison, but I have opted to avoid poison. This is out of respect for the endangered hawks and owls in my area, plus I fear my dogs getting into it. Plus it is an expense, albeit not a big one. Thus I use snap traps, feeding the dead mice to the chickens. The mice around here seem especially attracted to chocolate candy. Good bait.
Rats. Worse than mice not just because they are bigger, but because the get trap wise. Once they see a rat caught by a trap, they won't go near one. Rats are a constant problem because I live next to a macnut farm. The rats here live in trees and love macnuts. Every time the farmer sprays his trees or harvests his nuts, I have rats moving in. As with mice, I prefer to avoid using poison. I initially used snap traps, which the rats quickly learned to avoid. I caught a few here and there, but still had a major rat problem. I made all sorts of homemade trapping devices that I read about in books or on the Internet. They worked initially, but then the surviving rats got wise. Since the rats here are not crazy about ground grains, the idea of glass or plaster mixed into ground grain doesn't work. The best bait for rats on my farm turned out to be macnuts, macnut butter, and sharp cheddar cheese. I did come upon one trap that works for me. And since it does not cause the killed rat to bleed or scream, the other rats don't seem to learn about the danger. It is a zapper trap the works off of batteries. You smear bait on the back wall, that rat walks down the tube to reach the bait and in the process touches two metal plates. Zap. Electrocution.
Best rat control I now have are the farm cats. Since I hit upon the right combination and number of cats, I have zero rat problem. Zero. I will sometimes hear cats running on the roof at night and usually in the morning there will be a dead rat laying around someplace. Good cats! No more rats.
Fleas could also be considered vermin here. Because of feral cats and neighbors' dogs, fleas are an ongoing problem. In the past I have tried numerous ways of controlling fleas. But this is one area where I will willing spend the money to buy a flea controller that I know works. I use Advantage. Since my dogs and cats live communally, I don't need to apply it to everyone. By trial and error I've discovered which animals need to be treated and which get the benefit of protection from their sleeping buddy. By buying it in the large size, I can measure it out to treat several animals out of one applicator. Considering the farm maintains numerous cats and dogs, I get by cheaply in the flea control department.