Dung beetles are a large, diverse group of insects belonging to the Scarabaeidae family, known for their distinctive behavior of processing animal waste. These beetles are highly specialized in using the excrement of mammals, either for their own sustenance or as a provision for their offspring. Found on every continent except Antarctica, these insects display remarkable behaviors, including rolling dung into perfect spheres or burying it directly beneath the source. The widespread presence often leads to public concern about potential human interaction, particularly whether they pose a physical threat.
Assessing the Risk to Humans
Dung beetles are not aggressive and lack the specialized physical structures required to bite humans in a harmful manner. Their entire existence is centered on locating, manipulating, and consuming feces, meaning they are neither defensive nor offensive toward people or other large animals. The risk of receiving an injurious or painful bite from a dung beetle is negligible because their mouthparts are not adapted for piercing or tearing skin.
If a person handles a beetle, any sensation that feels like a “bite” is typically the insect’s strong mandibles attempting to grasp or manipulate the skin, similar to a small pinch or scrape. The beetle may also be trying to dig or burrow out of the hand using its powerful legs and head, creating a strong, pushing sensation. This behavior is simply a reflex to escape or manipulate material, not an attack.
Mouthpart Structure and Function
The mouthparts of adult dung beetles are highly specialized tools adapted for a soft, pasty diet, which is usually the excrement of vertebrates. This anatomy is centered around the need to process fine organic particles and microorganisms found within the dung’s liquid fraction. The structure involves a membranous and hairy labrum-epipharynx, along with mandibular incisor lobes, which are designed for manipulating the soft material.
The mandibles also feature molar areas that are finely ridged and function like a mortar-and-pestle system. This design is optimized for grinding and milling the organic particulates contained within the food. This grinding action extracts nutrients from the microorganisms and is entirely different from the strong, scissor-like mandibles of predatory beetles built to penetrate tough exoskeletons or hide.
Feeding Habits and Ecological Role
Dung beetles are classified as coprophagous insects, meaning their primary diet consists of feces, which provides necessary nutrients for adult feeding and larval development. They are broadly categorized into three behavioral groups based on how they process the dung: Rollers, Tunnelers, and Dwellers.
Behavioral Groups
Rollers (Telecoprids): Shape dung into a ball and roll it away from the pat to bury it at a distance.
Tunnelers (Paracoprids): Bury the dung directly beneath the source.
Dwellers (Endocoprids): Live and breed within the dung pat itself without moving or burying the material.
This intense focus on manipulating and consuming dung means their behavior naturally excludes interacting with humans. They are driven by the ephemeral nature of their food source, which must be secured quickly before it dries out or is utilized by competitors.
The activity of these beetles provides significant benefits to the ecosystem, serving as their primary role in nature. By burying and consuming feces, they rapidly remove waste from the surface, which helps control populations of pest flies, such as horn flies and face flies, that breed in manure. This burial action also contributes to nutrient cycling by incorporating organic matter back into the soil.
The ecological benefits of dung beetles include:
- Enhancing soil structure and promoting plant growth.
- Aerating the soil and improving drainage through the creation of tunnels.
- Contributing to secondary seed dispersal by burying seeds found within the dung far from the parent plant.