Dung beetles are the strongest animals in the world. They can pull 1,141 times their body weight. That’s like a human pulling six fully loaded double-decker buses. They are found on every continent except for Antarctica.
Unlike the dung beetles I watched with curiosity as a kid in Rhodesia (now Zimbabwe) that would roll a ball of elephant dung much larger than themselves, the dung beetles in North Carolina are mainly tunneling (lay eggs in the soil beneath the cow pat) or dwelling (lay eggs in the cow pat). Tunneling dung beetles are the most beneficial to soil and pasture health. By burying cow poo as food for their young, they aerate, introduce organic matter, and cycle the nutrients that are present in cow dung to the soil. The dwelling beetles have the additional benefit that they compete for manure with horn flies that can irritate the cows.
Dung beetles are great for pastures. Studies have shown Japanese Millet yields increased 81% and crude protein in bearded wheatgrass increased by 118% when dung beetles were present compared to cow dung alone. Another study has shown that you’d have to apply 200 lbs of Nitrogen per acre to see similar yields of coastal bermudagrass with dung beetle activity. At January 2021 average Nitrogen prices, a healthy dung beetle population would equate to a saving of $88/acre. With our 25 acres of fescue pastures (fescue has similar fertilization requirements to bermudagrass), that equates to a saving of $2,200 each year. Let’s reduce that by 1/3 and say $1465/year because even if we didn’t have dung beetles we would have still have dung. My neighbors that have large commercial chicken houses would debate this. They use their chicken litter to fertilize their cattle pasture for free. My counter argument is that you must get deep in debt to build one 600ft commercial chicken house (most build 2 or more).
When we did our first soil sample after moving here in 2014, the analysis by NCSU indicated the soil had high levels of Zinc and Copper from chicken litter that had been used as fertilizer. They advised not to fertilize with chicken litter anymore because high rates had been shown to stunt root growth over time, making the plants less resilient during periods of drought.
Relying on our dung beetle pasture network, we don’t buy fertilizer. If we did, I would ask the following questions of farms I was considering buying manure-based fertilizer from:
What goes in must come out, in this case onto pastures, and these questions will give me the information to decide if the fertilizer has anything in it that does not belong in the soil, in the plants, in the animals that eat the plants and in the people that we provide food for.
Balancing Cattle welfare and Dung Beetle welfare.
Controlling flies around cattle herds helps decrease the chance of disease spread and increase the general comfort of cattle. Ear tags infused with insecticides or pour-on treatments (similar to flea control applications in dogs and cats) are widely used for fly control. The problem is both kill dung beetles when excreted through dung, although ear tags seem to kill fewer in the short term than pour-ons. Persistent use of either, however, can negatively affect long-term dung beetle populations. Pyrethroid, which is a natural extract of chrysanthemum flowers, can be equally devastating to dung beetle populations.
As I mentioned previously, a healthy dung beetle population competes for the same manure as flies. Fly control leads to dung beetle death which leads to fewer beetles competing with flies which in turn leads to more flies and more insecticides to control them. As you can see, insecticide use becomes a vicious cycle. Conversely, our dung beetle population is very healthy because we don't use insecticides. We have seen anecdotal evidence of lower populations of horn flies over the seasons, although without some kind of controlled testing it’s hard to say what the season-on-season impact is.
When fly pressure is at it’s highest, we use a product called Ecto-Phyte which is a combination aromatic compounds and essential oils that creates a vapor around the cattle that acts as a shield. It’s not cheap, but we are using less of it each year and keeping the dung beetles safe as well. Of course the Pineywoods don’t like the smell and according to Sue it’s quite a comical watching me sneak up on or chase the herd to get close enough to spray them!
In addition to flies, cattle occasionally get gastrointestinal parasites which require treatment. A product such as Ivermectin which treats both parasites and flies kills dung beetles. In this respect we are fortunate to raise Pineywoods Cattle. They have not lost their ability yo graze for medicine. We have quite a few black walnut trees growing at the edge of the woods that they have access to and it is not uncommon to witness them taking a bite of the leaves, branches or bark. Black Walnut contains the natural anti-parasitic, jugulone, that helps control gastrointestinal worms. We have not been able to find any research that indicates jugulone has an adverse impact on dung beetles, but judging by the dozens of walnut fly larvae we find feeding on the rotted hulls of walnuts, it’s unlikely to have any long-term impact on dung beetle populations, especially considering the limited amount of black walnut the cattle eat.
Rootin' around poo for science and love
One of my projects for 2021 is to figure out how to count dung beetle populations so we can start measuring population health over time and secondarily relate populations to the nutrient levels in soil samples. I've tried to document beetle activity in the past by uncovering the top of cow patties so I could photograph them. I have yet to get one photo. As soon as I open one up the beetles immediately bury into the ground. I'm going to have to recruit Sue for help this summer, I reckon if she can open up the patty and I can focus solely on the photo I might have a chance.
I'm sure Sue won't be able to resist her offer of help, especially after I show her this wonderful Valentines card I made for her in the pasture (see below). I don't know how she puts up with me...