Guide to Fly Control for Dairy

It's Easier Than You Think to Win the Battle Against Flies!

There are over one million known species of insects in the world. Thankfully only a tiny percentage of insects are an issue for people and livestock. But those few insects can cause a major nuisance and seriously affect your profits whether you run a dairy, feedlot or are a grazier. This guide focuses exclusively on flies as they are the worst problem insects for most livestock owners.

The good news is that flies can be managed just like you manage every other element of your operation. Our belief is that effective fly control can make you money, not cost you money. You can not only gain a much more pleasant environment for your family, but by reducing fly stress the typical summer time fall off in milk production will be lower and often more than pay for the cost of good fly control. The same can be true for beef cattle as fewer flies usually means greater weight gain.

By gaining some basic understanding of fly biology, particularly what encourages and discourages their reproduction, you can reduce their numbers to tolerable levels, with no or only a minimum use of insecticides. Often the simple release of Fly Predators, plus modest improvements in manure management, is all that will be needed. More comprehensive approaches, including initial careful and selective use of insecticides, may be necessary for the fastest control if the pest fly problem has been allowed to become severe. This is because most of the "natural" controls prevent future flies, but do not affect existing adults. Since adult flies live approximately 21 days, you will either need to put up with them for that long or use traps and baits or careful pesticide application to reduce their population rapidly.

The House Fly and the Stable Fly are the primary pest fly species that create problems as well as being the most widely distributed.

Fortunately both of these can be very effectively controlled by good sanitation and Fly Predators. If sanitation is immaculate then fewer Fly Predators will be needed. Conversely, if "immaculate" is beyond practical then more Fly Predators and complimentary fly control products like bait, traps, and sticky paper can still yield satisfactory results.

Note, all other insects listed other than Horn and possibly Face Flies are not suitable hosts for Fly Predators and therefore Fly Predators will not help in their control.

The first step is to identify the insect(s) that are plaguing you and your animals. Most of the common pest flies are easy to identify simply by comparing one with the illustrations on the following pages. When the fly is identified, then use the methods listed that focus on the prevention and control of that species. This is important as the variety of flies that bother you can come from dramatically different sources. For example, House Flies primarily reproduce in moist (not too wet and not too dry) manure, but Biting Stable Flies reproduce in rotting vegetation (spoiled feed) and Horn Flies reproduce only in pastured cattle manure that is undisturbed. Knowing where to attack the problem is essential.

Basic Fly Biology

It’s been said that every creature has it’s purpose. For flies their purpose is to help decompose rotting organic matter such as manure, dead plants and animals. If you have an abundance of material needing decomposition, you get an abundance of flies. That’s why those in the Dairy and Beef business are more than familiar with flies.

Flies have four stages in their life cycle (shown at right). Adult House Flies lay eggs on or close to a larval food source of rotting organic matter (i.e., manure but also compost piles, rotting hay, etc.), the eggs hatch within hours into larvae (maggots). The larvae feed and then in no less than 5 days they pupate forming a cocoon. Inside this cocoon they metamorphose into an adult fly which takes at least 3 days. This is the same process a caterpillar goes through as it turns into a butterfly. You can use these minimum transformation days to your advantage.

The pupa is light to dark brown and looks very much like a dark grain of rice or a rodent dropping. This is the stage the Fly Predators take over and kill that immature fly. The pupa is also the stage that flies “hibernate” when the temperature drops below 47oF allowing them to make it through the winter. Note there are no “baby” flies, when they emerge from the pupa they are full size. The smaller flies you see are just different species. For example the House Fly has a smaller cousin, the Lesser House Fly.

Why Fly Control is Important

Flies are a major cause of discomfort and warm weather diseases of cattle and horses. Flies are found everywhere horses, cows, dogs, and other animals are concentrated and cause many problems. Some flies torture cows and your other animals by biting. Non biting flies irritate cows eyes, often causing serious infections such as pink eye. They are attracted to wounds, complicating them with infections. These insect pests also carry contagious disease from one animal to another.

On the following pages are ways and means of identifying, preventing and controlling these insects in and around your farm using an integrated pest management approach.