How Can Bugs Help Solve Murders?

It's a gross but very useful fact that some insects will eat deceased humans, because scientists can observe those insects to learn about where and when a person died. Learn about forensic entomology in this episode of BrainStuff, based on this article: https://science.howstuffworks.com/forensic-entomology.htm/printable

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Episode Transcript

Speaker 1 (00:01):
Welcome to Brainstuff, a production of iHeartRadio, Hey Brainstuff, Lauren
voblabam here. When investigators attempt to solve a mysterious event
involving sudden and unexpected death, they have to look at
clues in order to piece together the events. There are

(00:21):
a lot of questions to contend with what happened here
and when? Who committed this crime? Why? And what method,
weapons or tools did they use. With a vast background
of science, including biology, chemistry, physics, anthropology, and math, trained
specialists can look at the fragments of evidence left over

(00:43):
from a crime and with care and precision, construct a
legitimate story. They might use anything left of the crime scene,
including shards of broken glass, clumps of dirt, drops of
bodily fluids, and other trace elements. But one on or
around a victim's body that gets a lot of attention

(01:03):
during an investigation is actually a living organism, and it
usually comes after a crime is committed. We're talking about insects.
Bugs can tell us a lot about a death and
reveal details about a crime. Today we're looking at the
field a forensic etomology. Forensic etymology is the use of

(01:26):
insect evidence in both criminal and civil cases, and it
can help police and criminal investigators learn a great deal
about what happened to a body. That's because, just as
flies will flock to a piece of food left out
on a table, necrophilis insects or bugs that eat dead
flesh are often associated with human corpses. The major criminal

(01:49):
field of forensic anomology is known as medico legal anomology.
It's also known as forensic medical anomology or medico criminal
anomology because of its focus on violent crime. People working
in this field usually attempt to determine several important things,
but the keys are often the post mortem interval or
the estimated time of human death, and the location of

(02:11):
the death. These scientists may be called in on legal
cases involving mysterious sudden death where foul play is suspected,
traffic accidents with no apparent cause of crimes where insects
were introduced to a victim to cause harm, or even
less messy cases of insect damage to property or infestation

(02:31):
in food. But today we're talking about those messy cases.
Bugs will arrive very quickly to the orifices of a
deceased human body, such as the eyes, nose, ears and mouth.
Most insects can locate the smell of dead flesh within
a matter of hours after expiration as it starts to decompose,

(02:52):
and some insects, known as carrion insects, live their entire
lives feeding on dead flesh in order to fuel their
life cycle and create the generation of bugs. Adult carryon
insects mature and capable of flight will seek out the
nearest dead body to lay their eggs inside. After all,
it's got all the nutrientsa growing bug needs. There are

(03:15):
generally three stages an insect goes through during the part
of its lifetime that occurs inside of a dead body.
The first stage is the egg stage, where the insects
are still enclosed within their eggs. The second stage is
the larva stage, where the small, wiggly wormlike larvae that
have just hatched grow by feeding upon the dead flesh.
And the final stage is the pupa stage, which is

(03:38):
an intermediate stage that comes before the insect turns into
a winged adult and flies away. If an enomologist collects
insects from a corpse during any one of these stages, egg, larva,
or pupa, and if they understand the life cycle of
that type of insect, they can determine a fairly accurate
time of death. In other words, the enemal just needs

(04:00):
to understand two basic facts. How long after death the
insect eggs are generally laid, plus the amount of time
it takes for the insects to develop. These two facts
should give them a good idea of how long a
person has been dead. Many kinds of bugs may flock
to a decomposing body, but the most common kinds are
flies and beetles. Flies, like blowflies, can fine dead flesh

(04:24):
within minutes. A fly larva, commonly known as maggots, do
the majority of the eating and are responsible for much
of a corpse's decay. Beetles, on the other hand, will
typically move in once a corpse has dried out a
When collecting insects, investigators try to locate the largest specimens.
The oldest bugs should give the best post mortem interval

(04:47):
to preserve the insects. Samples taken from the body are
placed in containers filled with seventy percent isoprople alcohol, the
same strength as the rubbing alcohol solution you can buy
the store. The containers are labeled with the date and
time of the collection and the part of the body
from which the insects were taken. Then the investigator either
delivers the specimens directly to a specialist or mails the

(05:07):
containers expressly for examination. In a perfect situation, insects can
prove an easy tool for uncovering the unknown. For instance,
if a person dies of natural causes in a room
where the temperature has remained constant, and the coroner wants
to know the time of death, the entomologist simply looks
at the bugs around the corpse and reports the details.

(05:31):
It's almost never that easy, though. Investigators need to take
into account a large number of variables when collecting specimens.
The temperature of the surrounding area, for example, determines how
quickly larvae will grow in corpse. Oh when a person
is murdered during the summer months and left outside for
several days, the ambient temperature surrounding the corpse can change dramatically.

(05:54):
Certain types of blowflies develop faster during hot weather and
slower when it's cooler. A bus found on a body
that's been outside for weeks or even months showed drastic
variations in insect growth cycles, and an anomologist needs to
carefully observe the available specimens to determine a likely range. Meanwhile,

(06:15):
although many of the modern advancements in forensic science were
made in the late eighteen and early nineteen hundreds, perhaps
the first documented account of forensic etymology comes from the
twelve hundreds, a Chinese book from that period called The
Washing Away of Wrongs, where counts a murder in a
small village where the victim was badly cut. The local

(06:36):
death investigator asked around, but after several questions and few answers,
he decided to have each villager bring out their sickle
and lay it across the ground. Eventually, flies swarmed over
one sickle, and, most likely because its owner failed to
wash away microscopic bits of blood or tissue from the blade,
the killer confessed and the first known case of forensic

(06:59):
anomology was closed. Today's episode is based on the article
what do bugs have to do with Forensic Science? On
how Stuffworks dot Com written by John Fuller. Brain Stuff
is production of iHeartRadio in partnership with how Stuffworks dot
Com and is produced by Tyler Klang. Four more podcasts
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(07:21):
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