Identification of Common Arthropods in the Morgue

Nomenclature fun fact: the common names of true flies are written as two words (i.e. house fly, blow fly, etc.) while the common names of other insects that have "fly" in the name are written as one word (i.e. butterfly, mayfly, etc.) 

Phylum: Arthropoda

Characteristics include:

• Exoskeleton: composed of chiton; no internal bone structure
• Segmented Bodies: internal and external segementation
• Jointed Appendages
• Bilateral Symmetry
• ​Open Circulatory System (coelom)

Approximately 75% of all animals belong to this phylum which includes insects, arachnids, crustaceans, and myriapods!

Check out this basic morphology resource from the UNL Entomology Scientific Outreach Program to help with identification of key characteristics!

UNL Entomology Basic Insect Morphology

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(Jim Kalisch, UNL Entomology)

(UNL Entomology)

(Steve Spomer, UNL Entomology)

(Jim Kalisch, UNL Entomology)

(Jim Kalisch, UNL Entomology)

(UNL Entomology)

(Heather Smith from Pexels)

Don't see the insect you're looking for? You can send a picture to [email protected] or try this comprehensive identification tool!

Comprehensive Insect Identification Tool

Class Insecta

Necrophagous terrestrial insects can be helpful in determining a post mortem interval through the understanding of their lifecycles, habitats, and forensic succession. Identification of adult insects utilizes wing venation, antennae structure, vibrissae or bristles, tarsal distribution, and other physiological characteristics.  Some insect identification may require magnification  in order to determine the species, however, generally recognition to the order is helpful when determining forensic significance and also integrating pest management strategies within the morgue setting.  

Forensically Significant Insects (Terrestrial)

 

Diptera (Flies and Mosquitoes)

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Suborder Brachycera:

Overview

Lifecycle: Holometabolus
Forensic Significance: High

Adult Characteristics

• Antennae: filiform
• Eyes: large compound, sometimes meet on dorsal side of head
• Mouthparts: vary between sponging/lapping and piercing/sucking.
• Wings: pair of two front wings; reduced hind wings adapted to aid in balance, named halteres.
• Tarsi: 5-segmented
• Larger mesothorax due to increased flight ability and reliability 
• ​Vibrissae or bristles can be used for identification
  

Adults of almost all species are free-living and diurnal.  

Some species are predators of other Arthropods (i.e. robber flies) while others are external parasites feeding on the blood of human or animal hosts (i.e. mosquitoes, deer flies).​

Most flies oviposit in batches, though some species are known to give live birth (viviparous). 

​Blow Flies (Calliphoridae)

​Blow Flies : Calliphoridae

• Color: metallic body (Thorax NEVER has any black stripes on grey) 
• Vibrissae: hindmost humeral bristle located laterad of preustural bristle
• Usually 2 notopleural bristles
• Arista plumose beyond basal half
• Undeveloped postscutellum
  
  

Larvae feed on carrion and can often be found on or near orifices such as the nose, mouth, eyes, or genitalia.

Often referred to as "vultures" as the blow fly can cover up to 20km a day in search for food and are often the first insects present after death, appearing within minutes.
​
Blow flies can be sexed by observing the distance between their compound eyes; there will be a larger space between those of a female. 

GreenBottle Fly

Phaenicia sericata
Adult

• Metallic green color
• Suprasquamal ridge with tufts of hair 

Larvae

• oral sclerite is transparent therefore appearing absent
• Tubercle distribution of third instar larvae: distance between the two inner tubercles is the same as that between the inner and median tubercles 

Photo by Leon Higley, UNL Entomology

Photo by Leon Higley, UNL Entomology

Bluebottle fly

Calliphora sp.
Adult:

• Basicosta is black in color
• Hairs on the base region of jowls/side of mouth are gingery orange
• Anterior thorax spiracle is brown in color

Larvae:

• Width of posterior spiracles: spiracles are between 0.33 to 0.38 mm and are separated by less than the diameter of a single spiracle

Photo by Leon Higley, UNL Entomology

Blue Blow Fly

Cynomyopsis cadaverina

Photo by Jim Kalisch, UNL Entomology

Flesh Flies (Sarcophagidae)

• Color: greyish with three stripes down the thorax and a tessellated abdomen that is silvery-grey
• Larvae: barrel-like shape with posterior spiracles sunk into a hollow, large number of tubercles on posterior segment

​
There are three subfamilies (Spilza, Voss, and Pape), and adults are difficult to determine to species, but molecular methods can be applied.

House Flies (Muscidae)

Adult

• Color: frequently greyish in color with lines running down the length of their thorax
• Vibrissae: no hypoplural bristles
• Wing Venation: anal vein never reaches wing margin not curved, R5 cell is often narrowed apicall

House flies are often associated with human activity or livestock and their larvae feed on carrion, dung, etc. Adults of many species can be vector pathogens​ of diseases such as thyphoid fever, dysentry, anthrax, and African sleeping sickness. 

House flies can complete the life cycle in as little as 7-10 days and 10-12 generations can occur during warmer months of summer. 
Females can lay up to 500 eggs in batches of 75-150 over a 3-4 day period. 

​Adults live 15-25 days and are diurnal. 

House Fly

Musca domestica

Link to UNL House Fly Information

Photo by Jim Kalisch, UNL Entomology

House Fly Lifecycle Photo by Jim Kalisch, UNL Entomology

Humped back Flies (Phoridae)

• 1-7 mm in size
• Color: greyish brown or bluish in color
• Wings: veins 1 to 3 very pronounced, wing costa has a spine at the proxmial end
• Vibrissae: wide frons with robust, upward curving bristles
• Antennae: very short antennae (large third segment)
• Activity: often seen running quickly in short bursts followed by short pauses

​Some species are parasites of other arthropods including tarantulas, millipedes, and snails!

Larvae live in varying habitats which include moist or decomposing substrates, sewer pipes, trash cans in public restrooms, and even the digestive tract of animals including humans! 

Common names include "coffin fly" or "scuttle fly"

Sepsid Flies (Sepsidae)

• Color: shiny black
• Wing: unbroken costa
• Spherical head with convex eyes
• Abdominal constriction
• The male has elongated legs with spines

Characterized by tendency toward wing waving and may be seen in swarms. 

Cheese Skippers (Piophilidae)

Adult

• 2.5-4.5 mm
• Color: shiny black with yellow legs, antennae, and jowls
• Vibrissae: small, widely spaced ocellar bristles found opposite the simple eye
• Wing Venation: costal vein appears broken

Larvae

• Similar appearance to sepsid fly larvae but with a narrower posterior region
• Particularly characteristic behavior: larvae "jump" up to 15 cm in the air

 
The mechanical process of larval "jumping" occurs when the larvae are disturbed. They will bend toward their posterior end and grab the two papilliae located on this segment with their mouth hooks. When they suddenly release the papillae they appear to "jump" in the air. 

This insect is usually observed on the decedent at the end of active decay and the start of dry stages of decomposition. 

Piophila casei  is a common pest of cheese, hence, incombination with larval activity we get the common name of cheese skipper. 

Fannidae (latrine Flies)

Appearance is similar to small house flies. 

• Wing Venation: Sc diverges from R1 closer to wing base than Muscidae, 3A is curved outward distally.

Fannia canicularis, the lesser house fly, is attracted to light and commonly seen in homes. This species was also recorded in a case of child neglect suggesting the urine and feces attracted the adult flies which lead to myiasis (larval infestation) of the child's genitalia. 

Dung Flies (Sphaeroceridae)

• 1.5-5 mm
• Color: dull yellow or brown
• Antennae: segmented with an arista
• Wing Venation: costa has two breaks, vein 6 present but does not extend to wing margin
• Vibrissae: present on sides of mouth

Filter feed on bacteria and are attracted to ammonia. 

Have been noted from fresh, bloat, and advanced decomposition states between 4-8 months after death.

Soldier Flies (Stratiomyidae)

• 3 - 20 mm 
• body appears slightly flattened
• Wing Venation: wings fold over one another so the costal margins are parallel, costal vein stops at wing tip, discal cell in the middle of the wing veins
• Antennae: segmented, third segment is formed by several parts fused together
• Hermetia illucens adults have two translucent abdominal spots 

Larvae feed on detritus material and scavenge animal remains. 
All larvae have a calcium carbonate covering over the cuticle. 
Some species have aquatic larvae which thoracic spiracles and enclosed posterior spiracles  called siphons which iss urrounded by a halo of hairs that repel water. 

 

Coleoptera (Beetles)

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Overview

Lifecycle: 
Forensic Significance: High

Adult Characteristics

• Antennae: 
• Eyes: 
• Mouthparts: 
• Wings:
• Tarsi: 

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Forensically Significant Insects (Aquatic)

Aquatic environments are generally devoid of necrophagous insects but surfaces remaining under water can be utilized by aquatic insects. If the body reaches the floor of the aquatic substrate specific insect nymphs may predate or colonize the remains. During the release of gases, the body will rise to the surface allowing terrestrial insects access for predation while the aquatic nymphs continue below the surface of the water. Understanding of insect behavior, habitats, and life cycles can help determine time since submergence in aquatic environments. ​

Ephemeroptera (Mayflies)

Overview

Lifecycle: Hemimetabolous (incomplete metamorphosis)
Forensic Significance: aquatic juvenile stages

Development: 

• can take several months to several years
• stages include egg, nymph (3-6 months), pupa, subimago (a few hours to 1-2 days), and imago

Nymph Characteristics

• segmented body
• three pairs of legs attached to thorax with wing buds present
• three "tails" extending from abdomen

Habitat

• consume plant debris, algae, etc. attached to animal remains
• behavior varies upon feeding strategy:  burrowing in sediment, crawling on moss, clinging to rocks
• swimming ability ranges from very effective to incompetent

Adult mayflies have no forensic significance characteristically hold their wings vertically from the body. 

Trichoptera (Caddisflies)Trichoptera (Caddisflies)

Overview

Lifecycle: Holometabolous (complete metamorphosis)
Forensic Significance: aquatic juvenile stages

Development: 

• can take between six months - two years
• larval stage comprises 5 instars (6-10 months)
• pupal stage can take a few weeks - six months
• pharate adult stage swims to surface of the water and quickly matures to adult

Larvae Characteristics

• two fleshy protuberances extending from abdomen each ending in a hook with occasional additional hairs or anchor points. 
• some caddisflies are " case builders" and will create a case out of substrate to live inside
• long jointed legs on thorax

Habitat

• consume plant debris, algae, and some are carnivorous. 

Plecoptera (Stoneflies)

Overview

Lifecycle: Hemimetabolous (incomplete metamorphosis)
Forensic Significance: aquatic juvenile stages

Development: 

• can take up to three years to complete lifecycle
• egg (between 1 day to three months), nymphs (12-25 instars), 
• emerge in late spring and early midsummer

Nymph Characteristics

• 3 pairs of developed legs with two claws 
• two caudal tails at the end of the abdomen

Habitat

• stony substrate and good water quality
• slow-flowing rivers with muddy substrate and rooted vegetation
• stony rivers or streams, lake shores, etc. 

Diptera (True Flies including Midges and Mosquitoes)

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Additional Insects Observed in the Morgue

 

Dermaptera (Earwigs)

Overview

Lifecycle: 
Forensic Significance: 

Adult Characteristics

• Antennae: 
• Eyes: 
• Mouthparts: 
• Wings:
• Tarsi:

European Earwig  (Forficulidae)

 

Psocodea (Lice)

Hemiptera (True Bugs, including Bed Bugs)

 

Blattodea (Cockroaches)

 

Hymenoptera (Ants, Bees, & Wasps)

Coleoptera (Beetles)

Neuroptera (Net-winged Insects)

 

Orthoptera (Crickets & Grasshoppers)

Lepidoptera (Butterflies & Moths)

Class Arachnida (Spiders)

Wolf Spider

Common House Spider

Camel Spider

Class Crustacea

​ISOPODA (CRUSTACEANS)

Woodlice

​DECAPODA (CRAYFISH)

Class Myriapoda

Chilopoda (Centipedes)

Diplopoda (Millipedes)