Grazing in Michiana
It is the time of year when I like to talk about flies. They are frustrating, and I am not even the animal getting bit most of the time. I take the extra effort to kill flies this time of year. Each time I kill a fly it reminds me of the statistic: the descendants of one pair of flies, if all lived and reproduced normally, would cover the entire land area of the world to a depth of 18 feet in one summer.
Swatting a fly makes me think I am saving the animal world a lot of frustration. One of the most recent numbers I have seen was that flies cost the cattle industry $1 billion annually.
There are many methods for fly control and they all have their issues. On my farm, we would start around Memorial Day with a pour-on from the family of Avermectins. By this time, fly numbers are substantially increasing and an application to the back of cows would control flies for about one month. Technically the control will last longer, but for us, around the Fourth of July, we would bring the cows and calves through for vaccinations. At this point, animals would have insecticidal fly tags applied.
My wife's ranch family used to talk about insecticidal fly tags. They were introduced in the early 1980s, containing permethrin and fenvalerate, and they were extremely effective in keeping flies off of cattle. The tags were convenient, required minimal labor and provided control for an entire season. Within a few years, pyrethroid resistance was reported and these tags were no longer effective.
When a product is so good only a few flies live through their use, those limited flies find each other, mate and rapidly build up resistance. So, it is essential that the type of insecticide in these ear tags get rotated. There are generally three types, organophosphate, synthetic pyrethroids or macrocyclic lactone.
Most currently available fly tags offer protection for 12 to 15 weeks but are most effective during the first 45 to 60 days following application.
Fly tags applied too early in the grazing season may be largely expended and not offer enough protection during peak fly season. This is why I use the avermectins pour-on first, plus they give me parasitic worm control. This allows the use of fly tags later in the season so they still have some effectiveness into the fall.
The other type of fly control that I have used is the feed-through control as part of the mineral program. These use insect growth regulators that are effective on the fly larva developing in the manure. With this type of control, you are not going to see dead flies, and the process has to start well before the flies come out in the spring. Probably around April 10 in our area, it should be put out and then around Nov. 1, we could cease feeding this product.
I use all of the above, as my goal is to reduce flies both on the animal and in and around my house. Then I add another. In my chicken house and goat buildings, where animals get none of the above treatments, I put out the quarter-inch white sticky tape that comes in 600 hundred-foot wind-up rolls. I stretch out about 20 feet at a time. Flies accumulate on them to the point I have to roll out new tape sections about every other day. I appreciate their effectiveness.
There are other types of fly controls, including sprays, pour-on, back rubbers and dust bags. We have to be careful and make sure we are not using the same class of insecticides in all these methods. The chemicals have to be rotated. And the manure breeding sites need to be cleaned.
Horn flies and face flies are the major issues with cattle. There can be hundreds of these on an animal just biting away. On our farm, as we transitioned out of cattle into goats our flies also changed.
With goats, the major flies are stable flies and house flies. The stable fly has piercing mouth parts and feeds on blood several times a day, normally attacking the legs and belly. They are a lot less visible on the animal compared to the flies of cattle.
Stable flies take about three weeks to develop. Adult female flies can live 30 days and lay up to 400 eggs. Stable flies breed on organic debris such as wet straw, manure and spilled feed.
The house fly is non-biting. House flies also breed in organic matter including bedding, manure, decaying silage and spilled feed.
Out in the pasture or around the buildings, this summer will bring a plethora of flies. I will do my part to save the world from fly overload. Even in the house sometimes the vacuum is my weapon for control. Whoosh, and they are gone! Yes!