Kevin Jahnke, Jahnke Family Farm
Harriet Behar, Midwest Organic and Sustainable Education Service (MOSES)
Amanda Gervais, University of Vermont Extension
In this video, organic dairy farmer Kevin Jahnke demonstrates one of his management strategies for managing fly populations on his farm in Lancaster, Wisconsin. The video was filmed by Harriet Behar of the Midwest Organic and Sustainable Education Service (MOSES) who also conducted the interview with Kevin.
Watch the video clip at https://www.youtube.com/watch?v=1zuaDl7cR2g/p>
Kevin Jahnke: One of the things that I've devised on my farm for fly prevention is a thing that has come to be known as the "fly barrel." It's basically an expanded version of the little one gallon containers that you put in a bait for the attractant for the flies into it. The flies fly in, there's a little liquid in the bottom, they get trapped and they can't get out. So this is basically just an expanded version of that.
I took a 55 gallon barrel, cut a hole in the top and put in a piece of plexi-glass for the light so once the flies are in the barrel, they fly toward the light. There's about 8 to 10 inches of water in the bottom with a few drops of dish soap as a surfactant so when the flies get in it, they drown. And the entrance, there are four PVC pipes on the sides with elbows that go in and down, so flies fly into the barrel, they see the light from the top window, they fly toward the light and they don't know how to get out.
To get the fly barrel started, basically you just need to use something that doesn't smell very good, like some decomposing left-over food or something that gets in that barrel and starts to rot and smells really awful and the flies will go for it. And once you have enough flies in there, I just use a little aquarium fish net to dip out the dead flies. As the flies decompose in there, they continue to make their own attractant so all summer long when it's hot out, it smells pretty bad and fills up with flies.
Harriet Behar, MOSES: So how many flies did you get recently?
Kevin: I've got three barrels on my farm and the other day, I went around with a five-gallon bucket and my little dip net, and filled the whole five-gallon bucket full of flies that I took out of these three barrels. We tried to estimate how flies were in there and came up with a round figure of about a million flies, so I was pretty happy to think there were about a million flies weren't bugging my cows.
Harriet: How often do you have to clean out the fly traps? Does it depend on the time of year?
Kevin: Yes, it depends on the fly level. On a cool day like we are going to get today and the next few days, the fly levels really drop down and they stay pretty dormant. But when it's hot and dry and the flies are active, I might have to scoop them out every week. That's the nice thing about the barrels, once you have them started, there's really nothing to do, nothing to add, nothing to worry about, you just drive by and scoop out the flies and they keep working for you.
Harriet: And I see you have it near a place where the cattle will congregate, near the water tank here.
Kevin: Yes, when the cows come in, there's lots of flies on them and anytime the cows move around, they shake the flies off and the flies will look to congregate on solid, dark objects to stay warm. I've always noticed that this whole fence post will be covered with flies so I set the fly barrel right next to the post, and when the cows walk by, the whole side of the barrel becomes covered with flies, and as we're milking, the flies will slowly filter their way into the barrel.
The other thing I've noticed is that the color of the barrel makes a big difference. A darker barrel will attract flies from farther away because flies tend to look for a cow-like object, so they'll look for something dark.
And the dark barrel warms the inside of the barrel up to keep that bait that is in there really smelling nasty to keep drawing in the flies. I always have a fly barrel next to each water tank, and then I've got one other barrel that's portable that I will take around through the farm and where ever my cows have to be in the pasture, I will set that barrel in the vicinity there, and even leave it there a couple of days after to help clean up the flies that remain there.
Harriet: And probably too this probably prevents more flies from continuously reproducing?
Kevin: Right, it really helps break up the cycle. In addition to the fly barrel, with our rotational grazing system, I manage our pastures so that the cows aren't in one pasture close to the next, close to the next. They really hop around go from one end of the farm to the other because the flies tend to stay in the pasture when the cows leave. So if the cows don't go back to the pasture right next the flies, the flies don't find them as easy, so that just helps break the cycle.
Harriet: Or as quickly.
Kevin: Right. When we clip our pastures at this time of the year when the grass heads out and gets ahead of the cows, when we clip the pastures, I pull a small harrow behind the mower and that breaks up the manure patties, and doesn't give the flies to place to reproduce.
Harriet: Great, so let's look inside.
Kevin: Okay, so as you look in there, you're going to see a bunch of black, nasty stuff stuck on the sides. Basically whenever the wind blows really hard, it tips the barrel over and all of the flies that are there get stuck on the sides. You'll see the PVC elbows that the flies enter in. The stuff down at the bottom is where the flies get trapped. And there's a little piece of bait pouch that I hung there to help get some smell going again this spring.
Harriet: Excellent. Thank you, Kevin.