By Adam Varenhorst and Patrick Wagner et.al
There are several species of flies that can irritate and reduce the production value of livestock. The most problematic fly pests include face flies, stable flies, and horn flies. Alone or in combination, these flies can reduce milk production, calf weaning weights, transmit diseases [e.g., pink eye or infections bovine rhinotracheitis (IBR)], cause the development of sores, and affect grazing distribution. Fly population densities vary from year to year; however, they tend to be more of problem during hot, dry weather consistent with drought conditions. These conditions promote decreased development time that can effectively increase populations affecting livestock. To manage these pests, it’s important to be able to accurately identify them and understand their life cycles.
This article will focus on cattle, but many of the management strategies can also be applied to other livestock.
Stable Fly
Stable flies have mouthparts (proboscis) that protrude forward and are easily observed when the fly is at rest (Figure 1-A). Adults are slightly smaller than house flies but can be distinguished by their gray color and irregular black spots on the abdomen (Figure 1-B). When feeding on legs, stable flies almost always orient themselves so that their heads are facing upwards.
These flies require blood meals as adults, and their persistent feeding on the legs of cattle (Figure 2) often causes them to stomp their legs, bunch, or stand in water. As these behaviors disrupt grazing or feeding, they can lead to reductions in weight gain. Although stable flies can be found attacking pastured cattle, they are generally more of an issue for feedlots or dairies. This is due to the maggots develop in high moisture decaying organic matter, such as wet hay or manure. Areas with the highest maggot concentrations tend to be around feed bunks, stacks of hay, or manure piles.
Source : sdstate.edu