Thanksgiving is behind us, but here at MBHI, we’re thankful for bugs year-round. And that means all bugs, not just the charismatic butterflies and charming honeybees. We’re thankful for the spiders that show up in our homes and keep pests at bay. We’re thankful for the sheer abundance of herbivorous insects that feed larger animals in the food chain (even if they do a number on our gardens). And we are especially thankful for the underdogs: The insects and arthropods that live their lives mostly sight unseen, inhabiting the undergrowth and scavenging from the waste left behind by other organisms. Without the tireless work of these critters and other decomposers, we’d be drowning in refuse. And when it comes to this crucial cleanup crew, no bugs illicit a yuck-face quite like the humble dung beetle.
Most dung beetles belong to the family Scarabaeidae, the scarabs. This large family, consisting of over 35,000 known species, also contains the well-known and loved rhinoceros beetles. Some dung beetles even share a common trait with rhinoceros beetles, with many males exhibiting horns or antlers that they use to battle opponents. They compete over females, territory, and, of course, their coveted dung pats.
It’s difficult to imagine the scale at which these sometimes minuscule insects operate. Their work is thankless and largely overlooked, but if they suddenly disappeared from the planet, you’d notice. The cattle industry is a driving economic factor in the United States, with pasture and rangeland dominating 654 million acres, or 35% of the total land area. A single heifer can produce 9000 kg (or 19,800 lbs) of solid waste every year. And with 100 million cows roaming the land, that’s a lot of poop. But that waste has to go somewhere, and if you poke around in a fresh cow patty (preferably with a stick), you’ll find an entire network of critters at work.
Aesthetics are important, but dung beetles and other insects that consume and recycle dung are not just keeping our rangelands neat and tidy. Cattle dung is a breeding ground – literally – for pest species and harmful parasites. While dung will decompose on its own, the process is a slow crawl, and harmful organisms make full use of the time. In 1965, non-native dung beetles were introduced to Australia to tackle their dung problem. Cattle were brought to the continent in 1788, but with no native insects to feed on their waste, pastures slowly fouled, and pests like the Australian bush fly (Musca vetustissima) proliferated. After the dung beetle introduction, soil quality improved, and bush fly populations dropped a whopping 80%. Likewise, in a US study, dung beetles successfully reduced populations of parasitic nematodes that infect the gastrointestinal tract of cattle, a widespread challenge faced by livestock managers.
So, as we close out the holiday weekend and reflect on all the ecosystem services insects provide, don’t forget to include the underdogs: the dung eaters, the decomposers, the carrion control. They’ve provided free waste management services for millennia and will continue to do so as long as we care for them in return.