There are more than 350,000 species of beetles that inhabit the earth. In fact, the earliest known beetles existed around 230 million years ago. Some beetles are beneficial to plants, while others are pests to both plants and people. Black beetles are one of several colourful species of beetles. In general, beetles that live on the ground have a black colour that acts as camouflage. Although black beetles look similar at first glance, they can be distinguished by several characteristics such as habitat, behaviour and diet.
Black Ground Beetle
The black ground beetle, or Pterostichus melanariusalso, is also known as Carabid beetle. According to The Garden Safari, it is characterised by several vertical grooves across its wings. This beetle does not fly and can grow to over half an inch long. The black ground beetle inhabits woods, gardens and fields, living under leaves, on the trunks of old trees and beneath stones. The black ground beetle is a beneficial beetle as it preys on plant pests such as aphids, weevils, fly maggots and slugs. It occasionally eats earthworms and snails.
Black Rain Beetle
The black rain beetle, or Pleocoma puncticollis, makes its appearance on foothills and mountainous terrain at the first soaking of rain. These beetles measure around 1 inch in length. The male of the species has wings, while the females are wingless. The larvae of the black rain beetle are plant pests. They live in the root zone of the soil and feed on fibrous roots, main roots and underground portions of forest and orchard tree trunks, according to Washington State University.
Black Blister Beetle
The black blister beetle, or Cysteodemus armatus, is also known as the desert spider beetle because of its superficial resemblance to a spider. It has a three-segmented body comprising of a small head, a pitted back and an inflated abdomen. The black blister beetle derives its name from its defence mechanism, notes the Insect Identification website. When threatened, it produces cantharidin, a chemical that is toxic to humans and animals, and causes the skin to blister. Black blister beetles inhabit sandy riverbeds, and are plant pests that feed on alfalfa, wildflowers and weeds such as dandelion during bloom.
Black Carpet Beetle
The black carpet beetle ranges in colour from black to reddish brown, and is covered with short and sparse hair. It is oval and 1/8 inch in length. This beetle is a house pest and inhabits households during spring when it flies into the house. According to the University of Minnesota, adult beetles feed on pollen, and their larvae thrive on carcases and dried plant and animal material such as leather, wool, silk and feathers.