Question: if flies can spread disease then how do you control disease in the labs, and if you find maggots and flies around and in bodys can you tell how and when someone died ?

Katherine Davies answered on 23 Mar 2011:

Hi Hollie

Hope training is going well!

Different flies spread different diseases. The flies I work with do not carry malaria or anything like that, and as we breed them in house they are clean. Most of the flies in this country are not disease-spreading, so were ok.

In terms of determining when someone died, the flies are the best method to use after 48 hours after death. Flies lay their eggs on a body within hours of death, and because they are at the scene immediately after death, we can use the maggots (from the first laid eggs) to determine how long the person has been dead. For example, if you found 1cm maggots on a dead mouse in the garden, you could work out from their size that they would be roughly 4 days old (in the summer), so the mouse had been dead 4-5 days. If the maggots were only 2mm, then the mouse would have been there a couple of days. Using graphs, we can tell to the nearest hour or two how long the person has been dead, but this gives you an idea.

Flies only lay their eggs on body orifices, such as eyes, ears, nose and mouth, so if there is a large collection in the stomach for example, it could suggest that a large wound here may have been cause of death.

Hope this helps