Forensic Flies
The Blowflies
Blowflies (Family Calliphoridae)
Common name: blue/green bottles
l  Insect group most often used in forensic
investigations
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Extremely good at finding cadavers
Often the first to arrive
Generally associated with particular stages of
decomposition
Developmentally predictable
Lifehistory
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Adult – disperses, finds appropriate place to lay eggs
(cadaver)
Eggs – similar in texture to fine sawdust.
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Larvae (maggots)
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Crop
Usually laid (oviposited) in or near moist areas of the body
(especially the orifices of the head). Also found in hair or folds
of tissue or clothing.
Very small and often overlooked, especially early in
decomposition
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1st instar (stage) – small (>5mm), often overlooked
2nd instar (stage) 3rd instar (stage)
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Feeding
Post-feeding
Puparia
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A puparia is actually a pupa enclosed in the hardened skin of
the last stage maggot
Oviposition
Eggs
Female blowfly on
gunshot victim
Mass oviposition on
pig
Eggs in nasal passage
of homicide victim
First stage maggot
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Small to very small, often nearly transparent
Occur close to oviposition sites
May not be apparent if feeding in nasal
passages, throat, or other cryptic areas
Hatched eggs
Second Stage Larvae
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Larger and more opaque
Crop visible through skin
May form visible external masses,
although feeding is usually still
confined to discrete locations (face,
wound, etc.)
Top Down
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In general, an intact
cadaver without
external trauma will
be decomposed from
the head down and
from the core
outward to the
extremities
Colonization
Maggot
elsewhere may
indicate wounds,
pre/post-mortem
soiling, or sexual
trauma.
Extensive
colonization
of buttocks
Scrotum
Third Instar Maggot
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Final stage maggots feed voraciously
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Large numbers can form a ‘maggot mass’, a concentration of maggots
sufficient to generate significant heat through the action of proteolytic
enzymes
Once feeding has finished, the transparent crop will become
obscured by lipids
Maggots will then abandon the cadaver to seek sheltered
places to pupate.
Post-feeding
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After finishing feeding, 3rd instars transition into post
feeding larvae
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characterized by wandering behavior and fatty deposits under
skin
migrate "en masse" away from the body
strong excreted enzymes often mark the trail of migration
migration is usually in the direction of gravity
migration can be upwards of several feet to yards from the body
larvae attempt to burrow into substrate for protection
Puparia
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Once post-feeding larvae have decided on a location, the
puparia forms
At outdoor crime scenes, this may be in the soil, under the
cadaver, or under nearby debris
In indoor crime scenes, wandering maggots may be restricted
and puparia can occur anywhere on or off the cadaver
Adult Emergence
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Puparia may remain dormant for long periods of time (overwinter) or
adults may issue within 7-21 days (depending on the species and
temperature).
To emerge, the adult fly must break the puparia open along a preformed
line of weakness
Uses a ptilinum, an inflatable balloon on the front of head
Newly emerged flies are soft, the ptilinum is still visible, and are lighter in
color, a stage called ‘teneral’.
Teneral adults last point where the PMI can be accurately estimated.
ptilinum
Adult Identification
Tentative identification is possible for many
species using dichotomous keys
l  Confirmation of the identity of blowflies at the
species level is done by taxonomic or
forensic experts
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Important Species in Our
Region
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The ‘bluebottles’ Calliphora vomitoria and C. vicina
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C. vomitoria, rural, shaded, or wooded
C. vicina more urban, will enter dwellings
Black ‘cheeks’ orange beard
orange ‘cheeks’ black beard
The Greenbottles
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Lucilia coeruleiviridis, Lucilia (formerly Phaenicia)
sericata, Lucilia illustris
Cochliomyia macellaria
L. coruleiviridis
L. sericata
C. macellaria
L. illustris
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L. coruleiviridis one of the most common greenbottles in
eastern North America, L. illustris, rural / forested. L. sericata,
worldwide distribution, urban and rural, will enter dwellings
Cochliomyia macellaria (secondary screwworm)
‘Black’ blowflies
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Phormia regina, Protophormia terraenovae
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P. regina summer species at northern temperate
latitudes spring/fall in south.
Rural and urban, will enter dwellings.
Replaced by P. terraenovae at high altitudes and
latitudes
Phormia regina
Black spiracle
Protophormia terraenovae
Orange spiracle
Identification of Maggots
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Identification of 1st and 2nd stage maggots is very
difficult.
Maggots in general, have few external characteristics
that could be used to differentiate among species
Some third stage maggots are relatively easy to
identify
Head (anterior) End
Rear (posterior) End
Mouth hook and
denticular sclerites
Spiracles
Sampling the Scene