FREE online courses on the Basics to Forensic Entomology - Common arthropods
occurring on dead bodies
The Acari, or mites as they also are called, are small
organisms, usually less than a mm in length. Mites occur under the dead body in
the soil, during the later stages of decay. Many mites are transported to the
body via other insects, such as flies or beetles. Other mites are soil dwelling
forms which can be predators, fungus feeders or detritus feeders. Most species
will be found in soil samples from the seepage area under the body.
The Aranea or spiders are predators on insects occurring on
bodies. No species is specific to the carrion fauna, and will have limited or no
value in estimation of the PMI.
The order diptera contains insects with one pair of wings,
the second ones modified to halteres. About 100,000 species are known to
science, many more awaits discovery. Among the flies we find many members of the
carrion fauna. The larvae of flies lives in very different habitats, also
aquatic.
Trichoceridae
Trichocera sp.
or winter-gnats as they also are called because the common
species Trichocera regelationis, T. saltator, T. maculipennis,
etc, fly abundantly in the winter months, although they occur at lower
frequencies throughout the year. The adults resemble small crane-flies. The
larvae are saprophagous and feed on decaying material. Trichocerid larvae
constitutes an important part of the carrion fauna during the winter months,
when the blowfly fauna are missing.
Stratiomyidae
Larvae of Hermetia illucens is recorded eating on
human excrement and human remains. Usually this species occur late in the
decomposing process.
Phoridae
A large family of flies, containing about 3000 species. They
are minute to medium-sized (0.75-8.00 mm), dull black, brown or yellowish flies
of hump-backed appearance. They are generally bristly and with a very
characteristic wing venation. They run about in an active erratic manner which
has earned them the popular name of scuttle-flies. They breed in a wide variety
of decaying organic material, in addition some develop in fungi and others are
parasites. In the larval stage some species are predators. Several genera is
regularly found in vertebrate carrion e.g. Anevrina, Conicera,
Diplonevra,
Dohrniphora, Meopina, Triphleba and some Megaselia
species.
Conicera tibialis also known as the coffin-fly because
of its association with coffined bodies that have been underground for about a
year. Adult C. tibialis is able to bury to a depth of 50 cm in about four
days. At normal grave depths (1-2 m) temperature variation is slight, about 5
degrees Celsius, so development from egg to adult will take considerable time.
Development can take place independent of season, since the body is buried at
frost free depth.
Syrphidae
These are the familiar hover flies, often camouflaged as
wasps or bumble bees. Among the larvae of syrphids we find the famous rat-tailed
maggots. These occur in filthy water, and may occur in dead bodies.
Dryomyzidae
A small group of relatively rare flies. Most species are
found in moist woods. Their larvae occur in decaying organic matter.
Coelopidae
These flies are small to medium-sized, usually dark-brown or
black in color, and have the dorsum of the thorax flattened. The body and legs
are very bristly. They occur along the seashore and are very abundant where
seaweeds have washed up. Occasionally larvae may develop in other organic
matter, such as a dead body which has been lying along the seashore.
Heleomyzidae
Fairly large group of small to medium-sized often brownish
flies. Adults are often found in moist places, larvae in decaying plant or
animal matter, or in fungi.
Sepsidae
Very characteristic flies when alive, the adults occur in
large numbers around excrements and decaying materials, where the larvae
develops. The adults have a peculiar habit of wing-waving. This family have been
recorded feeding on dead human bodies in the time of caseic fermentation and
before ammoniacal fermentation. Eggs of Sepsidae have a very long respiratory
horn, often longer than the egg itself.
Sphaeroceridae
Minute or small dark flies that breed in dung.
Piohilidae
Dark, shining flies. The larvae are scavengers and are often
found on dead bodies that have been lying for a while. Piophila casei is
also called the Cheese-skipper, because the larvae jumps for a considerable
height, when disturbed. This behaviour is probably a defencive tactic against
predators. These flies also infests stored bacon and cheese, which, to the
flies, are almost the same as dried corpses.
Ephydridae
Large group with several common species. They are small to
very-small. Adults are found in moist places: marches, the shores of ponds and
streams, and the seashore. The larvae are aquatic, and many species occur in
brackish or even strongly saline or alkaline water.
Drosophilidae
These are the well-known fruitflies that every biologist have
heard about, and probably most other people too. Minute and small flies, brown,
yellow or grey with brightly colored eyes. The larvae feeds on decaying
vegetable matter, but some also feed on fungi. Some species may occasionally
occur on dead humans, and these are probably feeding on fungi.
Milichiidae
Minute, dark flies. Adults and larvae are scavengers.
Sarchophagidae
Among the Sarcophagids we find the large flesh-flies with red
eyes and a grey-checkered abdomen. These flies does not deposit eggs, but larvae
on the corpse. They are, together with the Calliphorids, among the first insects
to arrive at the corpse. The larvae are predators on blowfly larvae, as well as
carrion feeders. Many Sarcophagids are feeding on snails and earthworms.
Calliphoridae
These are the famous green-bottles and blue-bottles. There is
many species of blowflies, and each species has their own biology. Some prefers
to oviposit in shade, others in light. Some are mainly urban in their
distribution, others mainly rural.
Fanniidae
Here we find the lesser house-fly, Fannia canicularis
among others. These flies are mainly breeding in faeces, but can also develop in
cadavers, especially if there are patches with semiliquid tissue. The larvae
have fleshy processes all over the body, which assist in floating.
Muscidae
Among this large family we find the common house-fly,
Musca domestica. These flies occur in houses, and are one of the most widely
distributed species on this planet. In warm weather they can complete
development in 14 days. Eggs are laid in decaying material, including, but not
limited to, dead bodies.
Several beetles occur on carrion. There exists necrophagous
beetles and predators. The various groups occur in different stages of
decomposition.
Staphylinidae
Staphylinids - or rove-beetles may arrive a few hours after
death, and remain active throughout the decomposition process. The adult and
larvae feeds on eggs and larvae of other species. They have a characteristic
short elytra.
Dermestidae
Dermestids are common beetles in the later stages of
decomposition. Larvae of dermestids does not occur before the body is dry. The
larvae and adults feeds on dry skin and hairs and other dry dead organic animal
matter. Dermestids is a common stored product pest in homes, and a pest in
insect collections and furs at museums and other places.
Histeridae
Members of this family has short elytra, but not as short as
the Staphylinids. This family occurs wherever there is decay and putrefaction.
They have been found during the bloated, decay and early parts of the dry stage.
Both larvae and adults feed on maggots and puparia. They are usually concealed
under the corpse during daylight, but becomes active in the night. Saprinus
and Dendrophilus occur on dead animals and on air-dried and smoked foods.
They prey on larvae of Dermestes.
Silphidae
In this family we find the Nicrophorus species, well
known for their habit of undertaking small carcasses. Some of the species of
Nicrophorus
lives mainly on larger carcasses, and does not bury them. The adults prefer
feeding on maggots, but also feeds on the carrion. The adults feed their larvae
until pupariation. Easton reports that 13 specimens of Necrodes littoralis
was found on the body of a man which had been lying on the North Downs for 17
days in October 1969.
