What Do Dung Beetles Eat & How Do They Eat It?

Dung beetles eat animal feces, but not in the way most people picture. Adults consume only the liquid fraction and microscopic particles suspended in dung, filtering out the coarse plant fiber that makes up most of the pat. What they actually swallow is a slurry rich in microbes, partially digested nutrients, and tiny organic fragments, almost all smaller than the width of a human hair. And while dung is the headline food source, the family is more eclectic than its name suggests: some species have shifted to fruit, fungus, rotting carcasses, or even live prey.

What Adults Actually Swallow

If you watched a dung beetle feeding in slow motion, you would not see it taking bites of dung the way a cow chews grass. The beetle’s mouthparts are built for liquid processing. Mandibular molars press against the dung, squeezing out moisture along with suspended particles. Filtering structures, likely rows of fine setae, reject the coarse, mostly indigestible plant fibers. What passes through are particles so small that researchers had to use microscopic latex beads to measure them.

In experiments with Aphodius beetles, the maximum diameter of particles that had even a modest chance of being swallowed ranged from under 5 micrometers to about 25 micrometers, depending on the species.¹ Larger tunnelling and endocoprid scarab beetles showed the same general pattern: ingested particles maxed out between about 8 and 50 micrometers, with only a small increase in particle size as beetle body weight went up.² For context, 50 micrometers is roughly the thickness of a fine human hair. The beetles are not grinding or chewing the dung down to that size; tests showed no evidence that the mandibles actually break up dung particles before ingestion. Instead, the beetles are selecting already-tiny particles from a complex mixture and rejecting everything else.

So what are these tiny particles? The leading view is that they consist largely of microbial biomass and microbial debris, the bacteria and fungi that colonize dung, along with fine organic matter that has already been broken down by the herbivore’s gut. The beetle is, in a sense, harvesting the microbial community growing in the dung rather than eating the dung itself.³ Once the filtering removes coarse fibers and the squeezing eliminates excess water, what remains is a concentrated paste of the most nutritious fraction available.

How Larvae Eat Differently

The filtering system just described applies to adults. Larvae are a different story. Dung beetle grubs are bulk feeders: they chew through the dung mass without any apparent ability to separate tiny nutritious particles from coarse fiber.³ This means larvae ingest far more indigestible lignocellulose than adults do. How they extract enough nutrition from that roughage is still not entirely clear, but gut microbes are a major part of the answer.

Larvae rely on microbial symbionts to extract nutrients from vertebrate dung, and part of their microbiome is vertically inherited: the mother deposits a small fecal pellet in the brood ball, seeding the developing larva’s gut with her own bacteria.⁴ That inherited starter culture matters, but research shows that the diet the larva actually eats ends up shaping its gut community even more than what its mother passed along. The brood ball environment, in other words, is a fermentation chamber as much as it is a nursery.

The Gut Bacteria That Make It All Work

Even adult dung beetles need microbial help. The genome of the bull-headed dung beetle Onthophagus taurus, for instance, lacks the genes for making cellulases and xylanases, enzymes needed to break down plant cell walls. Its gut microbiome fills the gap, carrying biosynthesis pathways for amino acids and the very enzymes the beetle genome cannot produce.⁵ This is not just a convenient bonus; the beetle literally cannot digest its food without these bacteria.

How the gut is physically structured varies across species and relates to diet. A study of 21 Australian dung beetle species found that gut microbial diversity depended more on the beetle’s evolutionary lineage and the shape of its gut than on what it was currently eating.⁶ The most microbially diverse guts belonged to beetles in the genus Cephalodesmius, flightless species that have abandoned dung entirely and feed on composted leaf litter and other organic debris. Their hindguts have expanded into a specialized fermentation chamber, housing a highly conserved core set of bacteria that persists across isolated populations. That conserved community strongly suggests a long-term co-evolutionary relationship, not a random collection of hitchhikers.

Gut microbes also protect the brood ball itself. The gut communities of at least three dung beetle species showed antifungal activity against multiple plant-pathogenic fungi, suggesting that when a mother beetle coats the inside of a brood ball, her gut bacteria help fend off mold that could destroy her offspring’s food supply.⁷

Not All Dung Is Created Equal

If you are a dung beetle, the species that produced the dung matters a great deal. Chemical analyses of vertebrate feces from carnivores, omnivores, and herbivores show clear nutritional differences. Carnivore dung had the highest concentrations of amino acids, fatty acids, sterols, and cholesterol, along with the lowest carbon-to-nitrogen ratio, meaning more protein relative to indigestible fiber. Omnivore dung fell in the middle, and herbivore dung was the least nutrient-dense.⁸

You might expect dung beetles to flock to carnivore dung, then, but the picture is more complicated. Field experiments with pitfall traps consistently show that most species behave as generalists, visiting a range of dung types rather than specializing in one. Still, preferences emerge. One study found that elephant dung, which was exotic to the study region, was particularly attractive to beetles, while buffalo and wild boar dung also drew strong responses. Goat dung, by contrast, was the least attractive.⁹ The pattern suggests that dung beetles respond to a combination of moisture, nutrient content, volatile chemistry, and sheer volume rather than tracking a single nutritional metric.

How They Find It

Dung beetles locate their meals primarily by smell, and they are remarkably good at it. A fresh dung pat releases a complex bouquet of volatile organic compounds, and beetles detect those compounds through their antennae. Electroantennogram studies tested the antennal responses of 15 dung beetle species to 19 individual volatiles found in cow, horse, and rabbit dung. Every single compound tested triggered a measurable response, but the strength and pattern of those responses varied between species.¹⁰ A specific group of seven volatiles, including compounds like indole and p-cresol (the chemicals largely responsible for the “fecal smell” humans recognize), were the strongest drivers of distinct sensory profiles among beetles with different dietary preferences. In other words, species that prefer different types of dung appear to be tuned to slightly different scent signatures.

Rollers, Tunnellers, and Dwellers

How a dung beetle handles its food after finding it depends on which of three broad strategies it uses. Rollers sculpt a portion of dung into a ball and roll it away from the pat before burying it. Tunnellers dig directly beneath the pat and pack dung into underground chambers. Dwellers (or endocoprids) simply live and breed inside the dung pat itself, never moving the dung at all. These strategies sit within a hierarchy of competitive ability: large ball rollers and fast-burying tunnellers are dominant, aggressively removing dung from the pat before rivals can get to it. Smaller rollers are also effective. Slow-burying tunnellers and endocoprids, which take days to process the same amount, are competitively subordinate.¹¹

Competition at a fresh dung pat is intense and fast. In tropical environments, a pile of elephant dung can be colonized by thousands of beetles within minutes. The ball-rolling species invest heavily in speed: once they have carved out a ball, they need to get it away from the crowd before it is stolen. This is where their navigation abilities become relevant. African ball-rolling dung beetles have been shown to orient using the sun, the moon, celestial polarization patterns, and even the Milky Way. Under a planetarium dome, beetles rolled their balls along straight paths when only the band of the Milky Way was visible, but lost their bearings under overcast simulated skies.¹² Straight-line navigation is not about getting to a particular destination; it is about putting distance between the beetle and the mob at the dung pile as efficiently as possible.

When Dung Beetles Do Not Eat Dung

The name “dung beetle” is a generalization. Surveys in Peruvian rainforest found ten scarab beetle species that specialized exclusively on a single non-dung food resource, including fruit, fungus, carrion, dead invertebrates, and live millipedes.¹³ The most dramatic departure is predation. Deltochilum valgum, a species from the same Peruvian forests, has been observed killing and eating millipedes far larger than itself. It abandoned the ancestral ball-rolling behavior entirely; instead, it uses a modified head plate as a lever to disarticulate its prey, often by decapitation. In pitfall traps, D. valgum was attracted exclusively to millipedes and preferred injured individuals over healthy ones.¹⁴

Not every millipede-eating beetle is a killer, though. The South African species Chalconotus convexus readily consumes dead millipedes but cannot actually kill live ones.¹⁵ This distinction matters because it suggests different points along a spectrum: some species are scavengers that opportunistically eat whatever animal protein they encounter, while a few have evolved into genuine predators with modified anatomy to match.

Then there is the genus Pachysoma in the coastal deserts of South Africa, where large mammal dung is scarce. These beetles have given up dung almost entirely and instead drag dry plant litter back to underground burrows. One study of Pachysoma glentoni found that the buried detritus did not absorb soil water as researchers had expected; instead, the material arrived already containing moisture from nocturnal fog condensation.¹⁶ Dung beetles evolved in association with dung, but evolution does not care about job titles.

An Evolutionary Timeline

A popular idea holds that dung beetles originally fed on dinosaur droppings. Molecular phylogenetic evidence makes that unlikely. The lineages of plant-eating scarab beetles radiated first, roughly 100 to 108 million years ago, coinciding with the rise of flowering plants. The dung-feeding lineages came later: Scarabaeinae around 76 million years ago, and Aphodiinae around 50 million years ago, both well after the diversification of mammals that would have provided the dung.¹⁷ The clear time lag suggests a chain reaction: flowering plants fueled the expansion of herbivorous mammals, whose dung then provided the ecological opportunity for a secondary radiation of dung-feeding beetles. Dinosaur feces were probably not the original menu.

What Their Eating Habits Do for Ecosystems

Everything dung beetles do while feeding generates downstream effects. By burying dung underground, they move nitrogen, phosphorus, and other nutrients into the root zone of plants. A meta-analysis of 24 studies estimated that dung beetle activity increases plant growth by about 17% on average.¹⁸ The variation around that figure is wide, with some experiments showing little benefit and others showing dramatic gains, but the direction of the effect is consistent across most studies.

Their activity also reduces greenhouse gas emissions from dung pats. When beetles tunnel into and break apart a pat, they change its physical structure and microbial environment. One study found that dung beetle activity reduced methane emissions from individual cattle dung pats by about 14.5% and nitrous oxide by about 2%, giving an overall reduction of around 7% in CO₂ equivalents over the pat’s 59-day lifespan.¹⁹ A separate experiment using introduced dung beetles in a different system measured an even larger methane reduction: cumulative methane flux was 85% lower in beetle treatments compared to controls, and total greenhouse gas flux was nearly 18% lower.²⁰ The difference between those two figures reflects how much the result depends on beetle species, climate, and experimental design, but both show a meaningful effect.

Seeds that pass through fruit-eating mammals and land in dung also benefit. Dung beetles inadvertently move seeds horizontally and bury them vertically while processing dung pats. In one experiment, more than 97% of experimental seeds were moved horizontally, and over 55% were buried.²¹ This dispersal reduced the clumping of both seeds and seedlings, which theoretically protects them from predators and pathogens that target dense clusters. Whether that translates into more seedlings surviving in the short term remains uncertain, as the same experiment did not find a positive effect on establishment rates. Over longer timescales, though, burial may protect seeds from being eaten by rodents or desiccated by sun, and the nutrient-enriched soil around a buried brood ball could give seedlings a head start.

Parasite Control on Pastures

Farmers have long hoped that dung beetles could reduce livestock parasite loads by burying dung and disrupting the lifecycle of gastrointestinal nematodes whose larvae develop in dung pats and migrate onto surrounding grass. A field study in temperate pastures showed that by eight weeks, significantly fewer infective larvae were found around dung pats colonized by beetles compared to uncolonized pats, even with predominantly small endocoprid beetles of the genus Aphodius.²² Heavy rainfall, however, overrode the beetle effect, apparently washing larvae out of pats regardless of beetle activity.

The broader evidence is more cautious. A review of the literature concluded that meaningful reductions in nematode burdens in grazing ruminants have been documented only with the activity of large tunnellers that bury dung at least 15 centimeters below the surface. The overall scientific evidence for dung beetles playing a major role in controlling gastrointestinal nematodes in livestock is very limited and may have been overestimated in assessments of their ecosystem services.²³ Pest fly reduction, particularly of bush flies in Australia, has stronger evidence behind it.

Ivermectin and the Threat to Dung Beetle Populations

One of the biggest threats to dung beetle health comes, ironically, from the livestock whose dung they eat. Ivermectin, an antiparasitic drug widely used in cattle and sheep, passes through the animal’s gut and persists in the dung. Beetles feeding on ivermectin-laced dung suffer real physiological harm. Laboratory testing on dung beetles found that the concentration of ivermectin needed to halve their metabolic rate was just 0.24 micrograms per gram of dung, while the concentration needed to halve their ability to regulate body temperature was only slightly higher at 0.39 micrograms per gram.²⁴ These are low concentrations, well within the range found in dung from recently treated animals. A beetle that cannot regulate its temperature or sustain normal metabolic activity cannot compete at a dung pat, roll a ball, or dig a tunnel. The concern is not just that individual beetles are harmed; it is that routine antiparasitic use could quietly erode the beetle populations that provide the ecosystem services described above, from nutrient cycling to greenhouse gas reduction.

The timing of livestock treatment matters. Ivermectin concentrations in dung are highest in the days immediately after dosing and decline over weeks. Strategic timing of treatment, or switching to alternative drugs that break down faster, can reduce beetle exposure. Some countries have started factoring dung beetle welfare into veterinary guidelines, though this remains the exception rather than the norm.