Beetles have chewing mouthparts, and so do their larvae. These are two tough, approximately triangular jaws, which are able to exert powerful biting or grinding pressure. There is virtually nothing that beetles do not feed on.
What do beetles eat?
As well as scavenging in leaf litter, beetles eat plants from the roots to the shoots. They also tackle mammal dung, carrion, other insects and even each other.
Beetles graze mould in compost bins and are among the most important composting recyclers when it comes to dead wood and fungal decay. Some steal food from spiders’ webs. A few species invade our homes to infest our stored food and eat our carpets.
Beetles took advantage of the explosion in plant diversity with the evolution of flowering plants 120–100 million years ago, and now are the second most speciose plant-feeding insects after moth caterpillars.
Many of the over 135,000 specialist plant-feeders in the important beetle lineage Phytophaga are extremely host-specific. They will feed only on a single plant species – and often on just one part of that plant. In this way they have carved out tiny specialist niches, allowing diversification rather than competition with each other.
This does mean that some beetles have become serious garden or crop pests. Notorious examples include the lily beetle, Lilioceris lilii; the Colorado beetle, Leptinotarsa decemlineata, which devours potatoes; and the western corn root-worm, Diabrotica virgifera, which attacks maize. However, these ‘bad guys’ are the exceptions.
Main image: Dung beetle © Getty Images
