Overview

Carrion beetle is a common name for members of the beetle family Silphidae. These insects are primarily associated with dead animals: adults locate carcasses to feed and to provide resources for their offspring, and the larvae consume decaying flesh. Common names applied to different members of the family include carrion beetles, large carrion beetles and burying beetles (the latter especially for species of the genus Nicrophorus).

Taxonomy and diversity

The family Silphidae is usually divided into two main groups: the burying beetles (subfamily Nicrophorinae, including Nicrophorus) and the larger carrion beetles (subfamily Silphinae, including genera such as Silpha). There are over 180 described species worldwide, with the greatest diversity in temperate regions of the Northern Hemisphere. Species vary in size, coloration and habits, with some being strikingly patterned and others more subdued.

Distribution and habitat

Most carrion beetles occur in temperate climates and are common in grasslands, woodlands and hedgerows where vertebrate carcasses are available. In tropical regions many species occur at higher elevations or in cooler microhabitats. Deserts are typically poor habitat for silphids because of the scarcity of suitable carcasses and moisture. For regional species lists and distribution summaries see species information and distribution maps.

Appearance and identification

Carrion beetles show a range of body forms but share several diagnostic traits. Many have a flattened body and clubbed or capitate antennae that are sensitive to odours from decomposing tissue. In some species the elytra (wing covers) are shortened, leaving part of the abdomen exposed. Colouration ranges from plain dark browns to bright orange-and-black warning patterns in burying beetles. Flight capability differs among species: while many fly readily, some have reduced wings and move mainly on foot.

Life cycle and behaviour

Eggs are usually laid on or near a carcass so that the larvae have immediate access to food. Larvae feed on the flesh of the dead animal and pass through a series of moults before pupating in the soil. In many silphids adults visit carcasses primarily to feed or to oviposit; in other species the adults prepare the resource extensively.

Notably, certain burying beetles locate small vertebrate carcasses, bury them by working soil away and fashion the carcass into a nest for their young. Parents in these species often show prolonged care: they may remove fur or feathers, apply antimicrobial secretions, feed larvae by regurgitation and guard the brood. Such parental care, including biparental care in some Nicrophorus, is relatively rare among insects and has made these beetles a focus of behavioural studies.

Feeding interactions and ecological role

Carrion beetles contribute importantly to decomposition and nutrient cycling by consuming soft tissues and speeding the return of nutrients to soil. They interact with other necrophagous animals: at a carcass there can be competition with flies (Diptera), predation on fly larvae, and sequential colonization by different insect groups. Adult beetles of some species will also scavenge or prey on the larvae of other insects found at a resource; their presence can influence the local community of decomposers.

Forensic and applied importance

Because different species of carrion insects arrive and develop on remains in predictable sequences under particular climatic conditions, evidence from beetles and their larvae can be used in forensic entomology to help estimate the postmortem interval. Such estimates require careful consideration of species identification, developmental stage and local temperature records, and are normally used in combination with other lines of evidence. For background on larvae and development see larvae information and for adult foraging strategies and competition see adult behavior.

Conservation and research

Some carrion beetles are common and widespread, while others have restricted ranges and are vulnerable to habitat loss and changes in mammal communities. A well-known example is the American burying beetle, which has declined in parts of its original range and is the subject of conservation and reintroduction efforts. Silphids are also studied for insights into the evolution of parental care, chemical ecology (including antimicrobial behaviours) and community dynamics on carrion.

Notable distinctions

Carrion beetles are distinct from other necrophagous groups such as blow flies and dermestid beetles in body form, behaviour and, in some species, the presence of active parental care. The burying behaviour of Nicrophorus and the use of small carcasses as a resource are among their most characteristic and easily observed traits in temperate regions.

  • Family: Silphidae (two main subgroups: Nicrophorinae and Silphinae).
  • Diet: primarily necrophagous; adults and larvae consume carrion, with some predatory habits.
  • Role: decomposition, nutrient cycling, influence on other necrophages, forensic indicators.