A beetle on a leaf. Beetles are the group of insects in the order ????Coleoptera????, constituting about 25% of all known life-forms. 40% of all described insect species are beetles, about 350,000 and new species are frequently discovered. Beetles can be found in almost all habitats, but are not known to occur in the sea or in the Polar Regions. Certain species are agricultural pests, while other species of beetles are important controls of agricultural pests. Dhaka, Bangladesh. August 16, 2008.