The 4/8/13 repeat episode of Bones titled "The Partners in the Divorce" begins with Hodges finding 'blue blow flies'.
Entomology is a wonderful help to determine the PMI (post mortem interval) or the time since death.
There are tens of thousands of species of flies and it is important in Forensics what each one is attracted to. Some like fruit, some like defecation, some like putrification, etc.
The female blue blow fly smells the cadaverine, a gas released upon death, within minutes of its' release and can detect it within miles.
Flies don't have teeth so they use their tongues to suck the juices which is why they like the soft tissue areas or orifices like the mouth, nose, eyes, or wounds.
Not only do they feast but this is a great place for them to lay hundreds of eggs. The eggs hatch and become larva or what we normally call maggots. The larva can grow many times their original size and at the same time reduce the body mass of the food source (aka: victim).
Once the larva grow several stages (instars) they crawl to a dark quiet place to become pupa. They harden and look like brown or wild rice. They can be within feet of the body and in the dirt or folds of clothing. The next life cycle stage is that of the adult fly.
It is important for forensic entomologists to capture as many of the different stages of the fly that they can. They watch their captures through their stages in conjunction with the temperature of the scene to determine 'degree days'. This can give them a fairly accurate PMI.
Don't let it "bug" you, this is a great thing. The different species can also determine the travel path of some vegetative drugs and whether or not a victim may have been moved from one location to another.
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