Forensic Science Entomology Test
Terms in this set (36)
process in which an organism undergoes a rapid distinct change from young to adult form. Notable in the life histories of marine animals, insects and amphibians. It requires destruction and rebuilding of tissues, involving lysosomes, hormones and changes in gene expression.
Early instars or nymphs (egg case) --> Later instars (stage of growth)--> (cockroach) adult
Egg--> Early instar--> Larva or caterpillar (feeds on carrion)--> Pupa or Chrysalis (quiescent stage/inactivity)- does not feed or move)--> Adult (a significant change over life)-->Egg
Eggs hatch within 2-3 days. Egg stage is the first stage and 10-30 hours. Flies lay eggs on a corpse within minutes of its exposure.
developmental stage of a larval insect. As a larvae grows, it must periodically cast its exoskeleton. The stage between molts is called an instar. Flies undergo 3 instar stages as maggots, called the 1st, 2nd and 3rd instar, respectively.
Larvae, or maggots (or caterpillar), hatch from the eggs and increase in size by growth steps called INSTARS. The age of a larvae at collection minus the time of collection, may be the time of death (TOD).
larval instar (stage) of a fly or beetle. Fly larvae typically molt or change stages 3 times before pupation.
Eventually the larvae migrate from the corpse and develop into an inactive, pupal stage after which the adult fly emerges
Adults and larvae feed on carrion
Like body armor. It must be cast like a snake skin for the larva to grow.
organism that depends on the environment to maintain its body temperature. All arthropods, including
insects, are cold blooded. The development time from egg to adult depends on the temperature of their environment.
Contrast with warm blooded mammals and birds that control their body temperature through metabolic processes.
Process in which communities of plant and animal species in a particular area are replaced over time by a series of different and often more complex communities.
Post Mortem Interval (PMI)
the time elapsed between the death of a person and the discovery of the corpse. Blow flies can locate a corpse within 10-20 minutes of death. The time of first egg laying by these flies is consistent with the time of death.
Time of Death
By collecting and studying the ages and types of insects found on a body, a forensic
entomologist can predict the time of death. PMI can be used to determine the time of death. The TOD can be used to narrow the suspects in a crime. Suspects without an alibi would be in question. The age of a larvae at collection minus the time of collection, may be the time of death (TOD)
organic matter like a dead body. Flies that feed on CARRION (dead and decaying flesh) undergo complete metamorphosis. NECROPHAGOUS- feed directly on the corpse. Flies-Blow flies and flesh flies arrive minutes after death. Beetles-arrive later, after the body has begun to dry.
larvae's posterior breathing spiracles
Maggots act as DECOMPOSERS of organic
materials. Shorter, smaller maggots are
earlier instars. Longer maggots are later instars.
to lay an egg or eggs (of an insect)
feed directly on the corpse
Organisms feed on the maggots. Of Necrophagous species: Burying beetles (family Silphidae), Rove beetles (family Staphylinidae), Hister beetles (family Histeridae)
Live on or inside of the maggots. They kill the maggots. Of the Necrophagous species- attracted to other animals already feeding on the body-Mainly parasitic wasps
Use a net and sweep it back and forth over the decomposing body.
Collect a variety of maggots with forceps. Place them in boiling water to stretch them out and fix them.
Maggot samples are placed in containers
with food and reared to adult. Adult flies are easier to identify to species. Maggots can be analyzed for DNA and identified to species. Maggots can also be analyzed for the presence of drugs.
an illegal action on the part of a suspect.
Suspects without an alibi would be in question
individual who has died
the science of using insect evidence to uncover circumstances of interest to the low, often related to
a crime. Insects associated with a corpse can be used to determine time, location and/or cause of death.
Fresh- 1st Stage of Decomposition
begins at the moment of death (corpse looks like a sleeping person) and ends when the body becomes
visibly bloated. Blow flies (Calliphoridae) and flesh flies (Sarcophagidae) begin laying eggs during this stage.
Blow flies lay eggs but flesh flies deposit newly hatched larvae on the corpse.
Bloat- 2nd Stage of Decomposition
begins when the abdomen starts to show signs of inflation due to gasses produced by bacteria within the
gut. The greatest number of fly eggs are deposited during this stage. House flies (Muscidae) begin to lay eggs on the corpse. The internal temperature of the body rises to as much as 53 degrees C (127 degrees F) due to the action of internally feeding maggots and bacteria. The number and variety of predator beetles increases.
Active decay- 3rd Stage of Decomposition
marked by the breaking of the skin and escape of gasses. Due to the combined activity of maggot
and bacterial feeding. This stage smells bad due to production of decomposition gasses like putrecene and
Advanced decay- 4th Stage of Decomposition
fly larvae are completing their development and begin leaving the corpse to pupate. The temperature of the corpse drops and the remaining tissues are consumed. From this point on, most insect activity is due to beetles. Flies cannot feed on dry tissues.
Skeletonization- 5th Stage of Decomposition
only 10 percent or less of the original corpse remains, primarily composed of hair and bone.
Saponification- 6th Stage of Decomposition
condition in which the fatty tissues in a corpse are converted to a waxy layer similar in composition to soap (adipocere). Due to bacterial action and alkaline (basic) conditions from soil or embalming fluids in the absence of oxygen. Corpse can undergo saponification starting 2 weeks to 1 month after death. Usually occurs when a corpse is found in wet areas (eg. drowning victim) or after embalming. A corpse in this
condition is called a "soap mummy."
Mummification- 7th Stage of Decomposition
condition in which the body is preserved in an unusually dry place such that activity of internal bacteria or insect decomposers is kept to a minimum.
Dismemberment- 8th Stage of Decomposition
condition in which sections of a corpse have been separated. Can occur due to foul play or predators feeding on the corpse.
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