Most participants in pasture walks carefully avoid cow pies as they walk around observing the plant species and health of the pasture. Others, however, take special notice to the manure pats, checking for holes that indicate the presence of dung beetles.
Dung beetles play a small but remarkable role in the pasture eco-system. They feed on manure, use it to provide housing and food for their young, and improve nutrient cycling, soil structure, and forage growth in the meantime.
Researchers are finding that Dung beetles are important enough in manure and nutrient recycling that they well deserve the pasture manager's attention.
Mack Daeda, a UW-Madison student who plans to be a pharmacist, has accepted the challenge of studying dung beetles in a project at the Arlington Research farm.
During a recent pasture walk he described his project, noting their importance to the pasture's eco-system.
While some may wonder why a researcher would study dung beetles, he points out that most ruminants will not graze closely to manure pats.
If dung beetles are encouraged to live in the pasture, they can break up these cow pies in a short time, spreading out the nutrients and making the grass more palatable.
Research has shown that the forage is palatable, but avoided because of the dung pile.
Consequently, cattle manure deposits can make from 5-10 percent per acre per year unavailable. By completely and quickly removing the manure, dung beetles can significantly enhance grazing efficiency.
An adequate population and mix of species can remove a complete dung pile from the surface within 24 hours.
Describing his research, he points out that there are three groups of the beetles relevant to manure recycling.
"Probably the best-known group are the tumble bugs or rollers," he said. "In the behavior characteristic of this group, a male-female pair roll a ball of dung (brood ball) away from a manure pile in order to bury it."
Another group is the tunnelers, which he says typically bury the dung balls under the manure pat or close to the edge.
"Piles of soil next to the dung pat are indicators of tunneler-type dung beetle activity," he says. "Collectively, tunnelers and tumblers are classified as nesters because of their behavior in preparing a home for their young."
The third group of beetles that use dung are the dwellers. They live within the manure pat, engage in little to no digging, and generally do not form brood balls.
Adult dung beetles are drawn to manure by odor. Many are species prefer a certain type of animal manure.
They will fly up to 10 miles in search of just the right dung, and can attack dung pats within seconds after they drop. Some species will even hitch a ride near the tails of animals in anticipation of a deposit.
Once drawn by the odor, the adults use the liquid contents of the manure for their nourishment.
Daeda says Dung beetles benefits to livestock and the pasture environment just might outweigh their somewhat disgusting choice of food.
For example, manure is the breeding ground and incubator for horn flies and face flies, two economically important pests of cattle.
A single manure pat can generate 60-80 horn fly adults if protected from insect predators and competitors such as dung beetles.
As dung beetles feed, they compete with the fly larvae for food and physically damage the fly eggs. Fly populations have been shown to decrease significantly in areas with dung beetle activity.
The tunneling behavior of dung beetles increases the soils capacity to absorb and hold water, and their dung-handling activities enhance soil nutrient cycling.
The adult beetles lay eggs continuously for 1-3 years, depending on the species. Each will lay 60-80 eggs in her lifetime.
Adults generally do not survive the winter but eggs laid in the ground will survive winter. If they go to the next larvae stage, freezing could hurt the larvae.
Some graziers see enough of a benefit from dung beetles that they are willing to introduce them to their pastures.
Dan Schaefer, beef specialist at University of Wisconsin-Madison suggested that graziers protect dung beetles by avoiding dewormers that are harmful to them. Check the label to see if the product specifies that it will not harm the beneficial beetles.