Scarab beetles include the biggest insects in the world, in terms of sheer mass. Scarabs were revered in ancient Egypt as symbols of resurrection. More than just powerhouses, scarab beetles serve important roles in the habitats where they live.
The family Scarabaeidae includes dung beetles, June beetles, rhinoceros beetles, chafers, and flower scarabs.
What Are Scarab Beetles?
Most scarab beetles are robust, convex insects with brown or black coloring. Whatever the coloration, size, or shape, scarabs share a key common feature: lamellate antennae that can be closed tightly. The last 3 to 7 segments of each antenna form plates that can be expanded like a fan or folded together into a club.
Scarab beetle larvae, called grubs, are c-shaped and usually live in the ground, feeding on roots. The grubs have a distinctive head capsule, and easy to identify legs on the thorax.
The family of scarab beetles falls into the following classifications:
- Kingdom - Animalia
- Phylum - Arthropoda
- Class - Insecta
- Order - Coleoptera
- Family - Scarabaeidae
What Do Scarab Beetles Eat?
Most scarab beetles feed on a decomposing matter such as dung, fungi, or carrion. This makes them valuable in their environments as they are a bit like the cleanup crew or garbage haulers of the animal kingdom.
Other scarab beetles visit plants, feeding on pollen or sap. Flower scarabs are important pollinators, for example.
Larvae feed on plant roots, carrion, or dung, depending on the type of scarab.
The Life Cycle of Scarabs
Like all beetles, scarabs undergo complete metamorphosis with four stages of development: egg, larva, pupa, and adult.
Scarab beetles generally lay their eggs in the ground, in dung, or in other decomposing materials including carrion. In many species, the larvae feed on plant roots, though some feed directly on dung or carrion.
In areas with cold winter climates, grubs typically move deeper into the soil to survive freezing temperatures. They then emerge as adults in early summer.
Special Adaptations and Defenses
Some male scarabs, such as rhinoceros or Hercules beetles, bear "horns" on their head or pronotum (the hard dorsal plate covering the head-body junction). The horns are used to spar with other males over food or females.
Dung beetles excavate burrows below manure piles, then mold the dung into capsules in which they lay their eggs. The mother cares for her developing young by keeping the dung ball free of mold or fungi.
The June beetle (or June bug) feeds at night and is attracted to light, which is why they're often seen on warm evenings in early summer. The female can lay up to 200 small pearl-like eggs and the larvae feed on plant roots for three years before emerging as adults.
Some plant-eating scarabs such as the rose chafer are poisonous to chickens and other poultry who eat them.
Range and Distribution
Some 20,000 species of scarab beetles inhabit terrestrial habitats around the world. Well over 1,500 species of Scarabaeidae live in North America.