What Do Beetles Eat?

Written and verified by the biologist Samuel Sanchez

Last update: 18 November, 2023

Beetles are fascinating invertebrates, as they come in all sorts of shapes, sizes and colors. Their taxonomic group has an overwhelming variety, which is why they have colonized virtually every ecosystem on Earth. The question that concerns us here is simple: what do beetles eat?

Knowing the diet of beetles is interesting on many levels, as most species are responsible for recycling the decaying organic matter present in soils. If you want to know more about the feeding habits of these fascinating insects, read on.

What are beetles?

Before exploring their food choices, it’s good to know what beetles are. This common name encompasses all insects taxonomically categorized in the order Coleoptera, which has about 400,000 species. This is the most diverse animal taxon on Earth, representing 40% of all insects and 25% of all animal life forms.

Coleoptera are characterized by a hard exoskeleton and a pair of hardened forewings that serve as protection (elytra). Their body is divided into 3 sections; a head with horizontal mandibles, antennae, and compound eyes; a thorax with 3 pairs of legs and the insertion points for the wings (elytra and flying wings); and a segmented abdomen with respiratory spiracles.

Beetles are cosmopolitan and have colonized the vast majority of habitats on Earth, including coastal areas and freshwater environments. However, tropical ecosystems are generally considered to have the greatest variety of these invertebrates.

Beetles represent the largest and most diverse biological order on Earth.

What do beetles eat?

Answering what beetles eat is complex, as the diversity within this taxon is vast. Therefore, we’re going to show you the dietary choices of these animals based on their vital strategies. Don’t miss it!

1. Phytophagous beetles

The digestive system of most beetles is adapted to a herbivorous diet and digestion usually takes place in the midgut. Phytophagous beetles are those that feed mainly on plants, specifically on the tender shoots and leaves of shrubby plant matter.

The best-known representatives within this group are the carabids belonging to the subfamily Melolonthinae. These invertebrates usually feed on green and living plant tissues, but they don’t reject decaying wood and fruit if the opportunity arises. Some of these species have larvae with rhizophagous habits, i.e. they feed on roots.

Many beetles eat decaying plant matter, but not all of them feed on green, living leaves.

2. Polliniferous beetles

Polliniferous beetles are beetles that feed on flower pollen, the microscopic grains that contain reproductive gametes. The main representatives of this trophic adaptation are those belonging to the subfamily Cetoniinae. This taxon contains about 4000 species, although many remain to be described.

It is common to see polliniferous beetles visiting the flowers of different plants during the day. By feeding in this way they help the reproduction of various plant species, as they land on them and inadvertently fertilize them with pollen from another specimen.

3. Decomposer beetles

The vast majority of beetle larvae feed on decaying organic matter. This includes rotting wood, compost, dead leaves, fruits, and even meat or animal products present in the soil. However, some species carry out this trophic strategy also in their adult stage.

The subfamily Dynastinae is the subfamily that best represents the decomposer beetles. It has about 1500 species and 225 genera and its representatives are known in popular culture as rhinoceros beetles. Both larvae and adults feed on rotting wood, dead leaves, sap, fallen fruit, and humus in the soil.

The larval stage of these beetles can last for years, but the adults are often huge and fascinating.

4. Flesh-eating beetles

Flesh-eating beetles belong to the family Carabidae, a taxon containing about 40,000 species worldwide. These beetles stand out from the rest, as they tend to have a slender body, powerful jaws, and an admirable running speed to chase their prey.

Most carabids are nocturnal, because when the sun goes down they take the opportunity to leave their lairs and actively hunt their prey. Most are considered beneficial in the world of agriculture, as they kill pests without us having to resort to the use of chemical pesticides.

5. Necrophagous beetles

The term necrophagous refers to animals that feed on dead creatures. The beetles of the family Dermestidae are the best example of this within the group of Coleoptera. Although some of the species of this taxon are considered pests, others have specialized in eating dead flesh.

Some Dermestidae are used to clean corpses in the field of zoology, as they leave the bones of dead animals clean. They are also useful in the field of forensic medicine, as they allow investigators to calculate in a general way how long a victim has been dead.

6. Coprophagous beetles

We close this list with one of the most famous beetles on Earth. The dung beetles are a diverse group containing the taxa Geotrupidae, Scarabaeinae and Aphodiinae. These invertebrates inhabit many ecosystems, but are typical of grasslands, savannas, and deserts.

As their name suggests, these insects feed on the feces of herbivores and omnivores. Some of them make a ball with the feces and actively transport it to the shelter where the larvae are found, hence their name (dung beetles). However, sometimes they also feed on fruits, dead leaves, and toadstools.

As you can see, answering the question of what beetles eat is a complex task. Most species are herbivorous or phytophagous, but some show adaptations towards carnivorous habits or waste decomposition. Undoubtedly, this order of insects will never cease to surprise us.