Dung Beetles in West Virginia Pastures

Dung pats are incredible ecosystems, not only harboring potential problems for your livestock, like pathogens, internal parasites and insect parasites, but also beneficial organisms, like beetles. 

Dung-associated beetles 

There are five families of beetles that are associated with cattle dung in West Virginia pastures and provide critical ecosystem services: “true” dung beetles in the scarab family (family: Scarabaeidae, subfamilies Scarabaeinae and Aphodiinae), earth-boring scarabs (family: Geotrupidae), clown beetles (family: Histeridae), water scavenger beetles (family: Hydrophilidae) and rove beetles (family: Staphylinidae). 

True dung beetles in the family Scarabaeidae

Depending on the species, true dung beetles colonize patties within hours of pasture animals defecating ¹ and have three types of behaviors once they have colonized. “Tunneller” species bury brood balls in vertical chambers under or near dung patties. “Dweller” species stay within the dung to raise their young. “Roller” species show the most recognizable behavior by rolling their balls away before burying them ² (Figure 1). 

Figure 1. Diagram of dung beetle nesting behaviors. Image created with BioRender.com.

Rollers are often highly charismatic dung beetles and tend to have long back legs. These beetles will form a ball of dung and roll it away from the fierce competition in the dung pat to bury it. Males may do this alone, or with their female partners, and other males may try to steal it from them. Because of these fascinating behaviors, the ancient Egyptians worshiped dung beetles as a symbol of Ra or in the form of the god of the morning sun, Khepri, who pushed the sun across the sky, as the dung beetle pushes his ball. ³ While the Egyptians may not have understood the importance of dung beetles to the fertility of their soils, they did recognize their importance to life along the Nile. 

A common roller species in West Virginia pastures is Canthon piluarius (Figure 2). Adults (12 to 17 millimeters long) will fly to fresh dung pats, form a 2- to 3-centimeter ball of poop, and roll it away to bury 5 to 10 centimeters into the soil. These beetles have one generation per year. ⁴

Figure 2. Canthon piluarius, a roller species in West Virginia.

Tunneller beetles are more diverse than rollers in West Virginia. These beetles will create brood balls and bury them below the dung, sometimes more than 1 meter below the soil surface. ⁵ Once a female tunneller has chosen a mate, she and her partner dig below the dung to create a burrow. She then lays her eggs into their dung ball, where the eggs hatch and develop by eating that dung ball, pupating within it and emerging as an adult within a few weeks to a year. Some species of dung beetles will even stay with their brood-ball as adults to remove any mold that might start growing on the dung. ^5,6 Tunneling species in West Virginia include (but are not limited to) the Onthophagus hecate (scooped scarab), O. pennsylvanicus, O. taurus (bull-headed dung beetle, Figure 3), Copris species, the beautiful Phineas vindix (Rainbow dung beetle), and the impressive Dichotomius carolinus (Figure 4, Carolina copris). In West Virginia pastures, the most common tunneller species are Onthophagus hecate and O. taurus. 

Figure 3. Three common Onthophagus species: O. pennsylvanicus (left), O. taurus male (middle), O. hecate male top and side view (right).

Figure 4. Dichotomius carolinus, the largest dung beetle in West Virginia.

Dweller beetles (also known as endocoprids) lay their eggs directly into fresh dung, and the larvae develop either directly in dung or in brood balls within the pat. ² These are often in the group Aphodiinae and tend to be smaller beetles than rollers or tunnellers. Dwellers can be extremely numerous, with thousands coming to the smell of a single pat. We have many species of dweller beetles in West Virginia, including Aphodius fimetarius, Otophorus haemorrhoidalis and Oscarinus rusicola (Figure 5). 

Figure 5. Oscarinus rusicola, Aphodiinae species that is a dweller.

Other beetles found in dung pats

There are several other families of beetles that are important in dung pats. Beetles in the family Geotrupidae (Earth-boring dung beetles) have very similar behaviors to true dung beetles – they will bury dung balls and lay their eggs in them. In West Virginia, we have two common species: Geotrupes semiopacus and Geotrupes blackburnii. 

Histeridae (Clown beetles, Figure 6), Hydrophilidae (water scavenger beetles) and Staphylinidae (rove beetles) also are commonly found in dung pats. These three families include species that will feed on the dung itself, and other species that are voracious predators of insect eggs and larvae. Within Hydrophilidae, we find the predatory Sphaeridium lunantum and S. scarabaeoides commonly in fresh cattle dung in West Virginia. These two species will create holes in dung pats, giving manure a “cheese-grater” appearance (Figure 7). Beetles in the family Staphylinidae are extremely diverse and difficult to identify. 

Figure 6. Histeridae (clown beetle).

Figure 7. Dung pat with evidence of Sphaeridium activity (cheese grater appearance), and Sphaeridium scarabeoides swimming in fresh manure.

Role of dung beetle in pastures 

Dung beetles (Scarabaeidae and Geotrupidae) are important for pasture ecosystems and increase nutrient cycling and plant growth as well as structure dung for other organisms and reduce parasites. Feces are an excellent source of nitrogen. However, manure that stays on the soil surface can lose a lot of that nitrogen to microbes that release it as gas, rather than having it stay in the soil and be useful to plants. ^2,7 Because dung beetles mix nitrogen-rich feces into the soil, that nitrogen is more likely to stay in the soil than be released into the air. ^8-10 More nitrogen in the soil means more nitrogen for plants, and more plant growth. ¹¹ Having dung beetles in the ecosystem increases the biomass and nutritional value of pasture grasses for livestock. ¹²

Dung beetles not only move nitrogen down into the soil, but their tunnels help air and soil move up into the dung pats, increasing decomposition by other organisms like microbes. ² These tunnels also can improve water infiltration into the soil up to 30 centimeters down and decrease compaction. ^13-15

Because dung beetles eat manure, they can reduce cattle internal parasite transmission. Helminth parasites, like strongyle, Nematodirus spp, Trichuris spp, tapeworms and coccidia, infect new hosts when manure containing eggs and early-stage larvae are deposited in pastures. ¹⁶ These helminths will often move from the manure onto grasses and crawl up the stalk until they are eaten by grazing cattle. ¹⁷ Agg ressive dung beetle activity in the pat reduces helminth egg counts by four- to 50-times. ^18,19  

Other important cattle pests can be affected by beetles in dung as well. Parasitic flies like horn flies, Haematobia irritans, feed on blood, causing irritation and decreasing body condition, while face flies, Musca autumnalis, can transmit diseases like pink eye, eyeworms, mastitis and green-muscle disease within a herd. ²⁰ These flies lay eggs into fresh dung (zero- to one-day-old), where they develop to adulthood. Dung-associated beetles like water scavenging beetles (in West Virginia, Sphaeridium lunatum and S. scarabaeoides) and rove beetles are predators and will eat fly eggs and larvae. ^20,21 True dung beetles that feed on manure itself will out-compete dung-feeding flies by spreading and drying the pat so quickly that the flies are unable to complete their life cycle. In addition to helping reduce parasites, dung beetles can reduce the spread of Escherichia coli on broccoli by decreasing dung-feeding flies’ populations. ²²

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