chapter 13 forensics
Terms in this set (65)
study of insects
True of false: Humans are the most abundant and diverse forms of life on this earth?
False, insects are
how many described species are there?
over a million. more than 2/3 of known organisms
what are the two forms of metamorphosis
what is metamorphosis
egg--> larvae--> pupa--> insect
what are fly species of larvae?
what do larva look like?
a tubular object that looks like a worm
Define: forensic entomology
use of the insects and other arthropods that feed on decaying remains to aid legal investigations
what are the three types of forensic entomology
Urban (criminal and civil)
Stored product pests (civil)
what does medicolegal deal with?
what does urban deal with?
criminal and civil
what does stored product pests deal with
time between death and discovery of the corpse
uses of PMI
movement of the body
manner and cause of death
association of suspects of the scene
detection of toxins, drugs, or dna through insect larvae
what influences the decaying of a corpse?
depth of burial
access of insects
chemicals- embalming, insecticides, lime
animals- anything that could get to the corpse
difference between TOD and PMI
they may not equate
What is PMI restricted to?
time that the corpse has been exposed to an environment which would allow insect activity to begin
true of false: Time of death determines PMI
false, it is established by medical examiner
True of false: Time of death can be the same as PMI
true, if someone sees the person die
what are PMI conditions
time of day it occurs
time of year it occurs
whether or not the corpse is submerged
order of insects that arrive on the scene
Flies (order Diptera) are the first to arrive. Blowflies (F. Calliphoridae) and Flesh Flies (f. Sarcophagidae) are flesh feeders and will be
where do blowflies lay eggs if no trauma occurs
ears, nose, mouth, anus, genitalia
What do flesh flies do on a body
deposit larva. they do NOT lay eggs
what type of mouths do blow and flesh flies have?
what do blowfly eggs look like?
small 2-3 mm and are a whiteish yellowish
When it is cold are there more or less blowfly eggs?
usually how long does it take for blowfly eggs to hatch?
how does the body taper
anterior to posterior
Mouth at the anterior, spiracles at the posterior
what are spiracles?
a breathing technique
important for identification
when do blowfly larvae usually hatch
at the same time
where do the maggots start?
at the top of the head and move toward the stomach
changing of a larvae
how many instars do blowflies go through?
after the third instar what happens?
they crawl away from the corpse and burrow down into the soil to transform into the pupal stage and complete the life cycle.
characteristics of a pupa layer
it is the outer layer that hardens and shrinks
what happens inside the pupa?
the adult blowfly will form
What is roach track confusion?
Roaches are notorious for confusing blood spatter analysis
Blood trajectory is often critical to forensic investigations
what is flea dirt?
fleas feces that include undigested blood
what are insect stowaways
can allow investigators to track country of origin, and in many cases the local area of cultivation
how is PMI used to detect drugs?
in fly larvae that is consumed by corpses
When does the fresh stage begin?
at death, blowflies find the cadaver
manner of death
What is cause of death?
reason for death
mechanism of death?
is the specific change in the body that brought about the cessation of life
example of cause of death
what is an example for mechanism of death
the heart stop beating
factors that affect rigor mortis
ambient temp: hot- slows cold- speeds
clothing or lack of clothing: clothing speeds
sun exposure: speeds
body weight: obese- slows
chill of death
how to calculate algor mortis within first 12 hours
Temp loss= .78 degrees Celsius (1.4 degrees fahrenheit) per hour
how to calculate algor mortis after 12 hours
Temp loss=/39 celsius (.7 degrees fahrenheit) per hour
how is time of death expressed?
as a range of time
True of false: the longer the PMI is, the more accurate tod is?
what is the peak of rigor mortis
what is the reason someone dies?
cause of death
stage of life when when the larvae forms into a capsule turns into an adult
how long does it take a stomach to empty of food?
how many stages are there in human decomp?
what does a body look like in dry stage?
hair and bones
who is in charge of determining time of death?
what is the depositing or laying of eggs?
insects that play a larger role in late parts of decomp?
how long does it take for an egg to go to first instar
insects order of body
head thorax abdomen
emergence of an adult fly from pupal casting
what feeds on carrion