Carrion insects are those insects associated with decomposing remains. The processes of

decomposition Decomposition or rot is the process by which dead organic substances are broken down into simpler organic or inorganic matter such as carbon dioxide, water, simple sugars and mineral salts. The process is a part of the nutrient cycle and is e ...

begin within a few minutes of death. Decomposing remains offer a temporary, changing site of concentrated resources which are exploited by a wide range of organisms, of which

arthropod Arthropods (, (gen. ποδός)) are invertebrate animals with an exoskeleton, a Segmentation (biology), segmented body, and paired jointed appendages. Arthropods form the phylum Arthropoda. They are distinguished by their jointed limbs and Arth ...

s are often the first to arrive and the predominant exploitive group. However, not all arthropods found on or near decomposing remains will have an active role in the decay process.

Ecological roles

Carrion insects are commonly described based on their ecological role. Four commonly described roles are: #

Necrophagous Scavengers are animals that consume dead organisms that have died from causes other than predation or have been killed by other predators. While scavenging generally refers to carnivores feeding on carrion, it is also a herbivorous feeding b ...

species # Predators and

parasites Parasitism is a Symbiosis, close relationship between species, where one organism, the parasite, lives on or inside another organism, the Host (biology), host, causing it some harm, and is Adaptation, adapted structurally to this way of lif ...

of necrophagous species #

Omnivorous An omnivore () is an animal that has the ability to eat and survive on both plant and animal matter. Obtaining energy and nutrients from plant and animal matter, omnivores digest carbohydrates, protein, fat, and fiber, and metabolize the nutri ...

species # Adventive species

Necrophagous species

Necrophagous species are insects/arthropods that feed directly on remains, or the fluids released from remains during the decomposition process. This ecological classification includes many species of the order

Diptera Flies are insects of the order Diptera, the name being derived from the Greek δι- ''di-'' "two", and πτερόν ''pteron'' "wing". Insects of this order use only a single pair of wings to fly, the hindwings having evolved into advanced ...

(true flies) from the families

Calliphoridae The Calliphoridae (commonly known as blow flies, blow-flies, carrion flies, bluebottles, greenbottles, or cluster flies) are a family of insects in the order Diptera, with almost 1,900 known species. The maggot larvae, often used as fishing ba ...

(blowflies) and

Sarcophagidae Sarcophagidae () are a family of flies commonly known as flesh flies. They differ from most flies in that they are ovoviviparous, opportunistically depositing hatched or hatching maggots instead of eggs on carrion, dung, decaying material, or op ...

(flesh flies), and some species of the order

Coleoptera Beetles are insects that form the order Coleoptera (), in the superorder Endopterygota. Their front pair of wings are hardened into wing-cases, elytra, distinguishing them from most other insects. The Coleoptera, with about 400,000 describ ...

(beetles). Although specific arthropod species present at remains will vary by geographic location, some examples of common blowflies are ''

Calliphora vicina ''Calliphora vicina'' is a member of the family Calliphoridae, which includes blow flies and bottle flies. These flies are important in the field of forensic entomology, being used to estimate the time of a person's death when a corpse is found a ...

'', ''

Phormia regina ''Phormia regina'', the black blow fly, belongs to the blow fly family Calliphoridae and was first described by Johann Wilhelm Meigen. The black blow fly's wings are specialized with a sharp bend. These flies are also have well-developed calypt ...

'', ''

Protophormia terraenovae ''Protophormia terraenovae'' is commonly called northern blowfly, blue-bottle fly or blue-assed fly (blue-arsed fly in British English). It is distinguished by its deep blue coloration and large size and is an important species throughout the No ...

'' and ''Lucilia sericata'' Necrophagous blowfly species are often the first to arrive and colonize at a site of decomposing remains. These species develop from eggs laid directly on the carcass and complete their life cycle on or near the remains. Because of this, necrophagous species are considered to be the most important for post-mortem interval estimations. The initial colonizers of greatest importance are those of the family Calliphoridae, Sarcophagidae and

Muscidae Muscidae are a family of flies found in the superfamily Muscoidea. Muscidae, some of which are commonly known as house flies or stable flies due to their synanthropy, are worldwide in distribution and contain almost 4,000 described species i ...

(house flies), as these are typically the first insects to lay eggs at remains. The fresh stage of decomposition is characterized by the arrival of necrophagous blowflies and flesh flies. These blowflies are also strongly attracted during the bloat stage of decomposition. Many Dipterans, especially their larval forms, are involved in removal of material from the carcass, though not in an appreciable amount. Necrophagous species of Coleoptera are most strongly attracted during the active stage of decomposition.

Predators and parasites of necrophagous species

This role includes those insects which feed on, or act as parasites of, necrophagous species. These insects do not feed directly on the decomposing remains or its fluids, but are considered to be the second most forensically important ecological role. Predators of necrophagous insects include species from the Coleoptera families

Silphidae Silphidae is a family of beetles that are known commonly as large carrion beetles, carrion beetles or burying beetles. There are two subfamilies: Silphinae and Nicrophorinae. Nicrophorines are sometimes known as sexton beetles. The number of sp ...

(carrion beetles) and

Staphylinidae The rove beetles are a family (Staphylinidae) of beetles, primarily distinguished by their short elytra (wing covers) that typically leave more than half of their abdominal segments exposed. With roughly 63,000 species in thousands of genera, the ...

(rove beetles). Parasites may include species of parasitic wasps, from the order

Hymenoptera Hymenoptera is a large order (biology), order of insects, comprising the sawfly, sawflies, wasps, bees, and ants. Over 150,000 living species of Hymenoptera have been described, in addition to over 2,000 extinct ones. Many of the species are Par ...

(family

Braconidae The Braconidae are a family of parasitoid wasps. After the closely related Ichneumonidae, braconids make up the second-largest family in the order Hymenoptera, with about 17,000 recognized species and many thousands more undescribed. One analysis ...

). Some species of blowflies may begin their larval development in the necrophagous role, feeding directly on remains, but become predaceous during later larval stages. These species are listed as being schizophagous, and are included in the predators and parasites ecological role. The majority of beetles present at remains are there as predators of blowfly larvae, and are not directly concerned with the removal of carcass materials. Predaceous beetles may arrive at a site of remains as early as the bloat stage of decomposition, when there is a strong attraction of their necrophagous prey. Some of these species may also remain during active decay. During the advanced stage of decay there is an increase in those insects which are predaceous and/or parasitic on necrophagous beetles.

Omnivorous species

Omnivorous species feed on both the decomposing remains as well as other carrion associated insects, usually necrophagous species. Large numbers of omnivorous insects can slow the rate at which carcass materials are removed by depleting the number of necrophagous larvae. This category includes species of

ant Ants are eusocial insects of the family Formicidae and, along with the related wasps and bees, belong to the order Hymenoptera. Ants evolved from vespoid wasp ancestors in the Cretaceous period. More than 13,800 of an estimated total of 22 ...

wasp A wasp is any insect of the narrow-waisted suborder Apocrita of the order Hymenoptera which is neither a bee nor an ant; this excludes the broad-waisted sawflies (Symphyta), which look somewhat like wasps, but are in a separate suborder. Th ...

s, and some species of carrion beetles.

Adventive species

Adventive species may or may not play a significant role in the decomposition of remains. Arthropods in this ecological role are not necessarily attracted to decaying remains, but use it as an extension of their natural habitats. Adventive species originate within the vegetation and soils surrounding decomposing remains. These insects may visit remains from time to time, or use them for concealment, but their presence can only be accounted for by chance. They may also become predators of necrophagous species found at remains. Adventive species include

springtail Springtails (Collembola) form the largest of the three lineages of modern hexapods that are no longer considered insects (the other two are the Protura and Diplura). Although the three orders are sometimes grouped together in a class called Ento ...

centipede Centipedes (from New Latin , "hundred", and Latin , " foot") are predatory arthropods belonging to the class Chilopoda (Ancient Greek , ''kheilos'', lip, and New Latin suffix , "foot", describing the forcipules) of the subphylum Myriapoda, an ...

s and

spider Spiders ( order Araneae) are air-breathing arthropods that have eight legs, chelicerae with fangs generally able to inject venom, and spinnerets that extrude silk. They are the largest order of arachnids and rank seventh in total species ...

s. The diagram below shows the relationship between each ecological role and a site of decaying remains. Carrion insect trophic relationships

Condensed ecological roles

The ecological roles described above can further be condensed into two broad, general classifications: # Properly cadaveric entomofauna # Arbitrary entomofauna of a cadaver

Properly cadaveric entomofauna

This classification consists of necrobiont insects which use decaying remains as a permanent environment necessary for their life and development. Necrobiont insects includes necrophagous and entomophagous trophic specializations, or necrophagous, predaceous/parasitic and omnivorous species.

Arbitrary entomofauna of a cadaver

Some insects or arthropods visit sites of carrion, but do not colonize them. This classification consists of those insects for which decomposing remains are not a permanent feature for development. The adventive trophic specialization falls into this category.

Forensic relevance

Each group or species of insect will be attracted to decomposing remains at different stages of decomposition, as changes within the remains result in the availability of different resources. The predictable order in which the above described insect groups are attracted to and observed on remains is referred to as a succession pattern, and can be used in forensic investigations to estimate the

post-mortem interval The post-mortem interval (PMI) is the time that has elapsed since an individual's death. When the time of death is not known, the interval may be estimated, and so an approximate time of death established. Postmortem interval estimations can ra ...

(PMI) or time since death. This method of PMI estimation is most useful in the later stages of decomposition. A second method of PMI determination, in early stages of decomposition, by insect evidence utilizes the development rate of colonizing arthropods. This method is usually applied to necrophagous blowflies, as they are often the first to colonize and are associated with remains for the longest period. Development rates are only useful in forensic investigations until the first new generation has completed development and left the remains.

References

{{DEFAULTSORT:Carrion Insects Forensic entomology Insect ecology Medical aspects of death