Scarab monument, Egypt © Ben Pirard
Depending on the species, dung beetles have different strategies for surviving the winter. Many overwinter as mature adults, buried deep in the soil beneath the freeze line. Others remain in their larval form, slowly completing metamorphosis in pupal cells until spring approaches. In some cases, eggs that were laid in late summer remain in a state of suspended animation until freezing temperatures have passed.
Technically speaking, dung beetles are coprophagous—manure eating—scarab beetles. Millennia ago, they were revered by the ancient Egyptians as the symbolic manifestation of Khepri, the scarab-faced god who rolled the sun across the sky each day. And like actual dung beetles moving a ball from point A to B, Khepri’s ball of sunlight was buried below the horizon, bringing forth the night. In more recent times, these charismatic scarabs have been of interest to homesteaders and producers here in North America.
The April 1, 1911 issue of “Country Life in America” featured an article entitled “Tumblebugs at work,” in which the author—Simeon Singleton— waxes po(o)etic about dung beetles. “I…watched the curious antics of the tumblebugs in their diligent endeavors…after a pair of rollers had their prize stolen by a rival beetle, the smaller of the pair of beetles grabbed the offender and held him securely while its mate climbed on his head and with his mandibles rained blows that I could plainly hear.” Such drama!
We’ve learned a tremendous amount about dung beetles since the days of ancient Egypt. We now know that some species navigate by starlight and align their movements with the Milky Way. We’ve discovered there are tunnelers, dwellers, and rollers that all use manure in different ways. There are cuckoo dung beetles that wait for other species to do the hard work and then swoop in and lay their eggs on another beetle’s prize. There are even plants whose seeds mimic balls of dung both in smell and appearance, tricking beetles into dispersing and burying the capsules, thus planting the next generation.
Perhaps even more interesting to our readers is that dung beetles save the U.S. ranching community an estimated $380 million dollars each year. These helpful critters present a number of important services for producers including nutrient recycling and increasing grazing opportunities due to waste removal. Without removal, dung pats make 5-10% of a pasture unavailable because cattle avoid grazing among cow pats. A lack of pat removal also changes plant composition when dung coverage is heavy. When dung beetles break down pats, cattle pests such as horn and face flies are also kept at bay since there is less food available for their maggots to feed on.
Generally speaking, dung beetles are great biological indicators of healthy grasslands. The greater the dung beetle diversity in a prairie ecosystem, the greater the likelihood that it is healthy. However, these insects are surprisingly sensitive to pesticides. As a result, they are one of the fastest declining groups of land-dwelling insects in the world. Pesticides such as ivermectin, which are administered to cattle and then passed into the feces, are some of the greatest killers of dung beetles. An estimated half-life for degradation of this chemical in the soil is 127 days although it can vary depending on the season. Ivermectin has also been shown to slow the decay of dung. Neonicotinoids—a systemic pesticide used to treat crops—also appear to be another major player in their decline.
As spring approaches and winter thaws, keep an eye out for those hard working rollers, tumblers, and dwellers. The more species you have, the healthier your rangeland is likely to be. For a free, printable pocket guide, follow this link to the SDSU Extension Guide, for a more detailed online guide go here, or to submit photos for identification of any species of plant or animal that you find on your ranch (including dung beetles) download Seek, an amazing, free phone app that can identify many species right away by simply using your camera phone.
