What do entomologists do at a crime scene?

Answer 1

There may be any number of uses for an entomologist at a crime scene. But most typically, their expertise is used to help determine how long a body has been deceased, and how long it has been at the scene.

For example, by examining the degree to which flies have been reproducing on/in the corpse, they can determine how long the body has been dead. If there are no live maggots present, then the flies have not had much time to lay eggs and hatch them, and therefore the body cannot have been dead for very long.

Or, let's say you find a body in the woods that is badly decomposed, but, there are NO maggots on it. Clearly, the body cannot have been recently deceased, because it is so obviously badly decomposed. The absence of maggots would thus indicate that the body had been wrapped up and stored somewhere where flies could not land on it -- maybe wrapped in plastic garbage bags and stuffed into an old, broken refrigerator -- and then moved and dumped in the woods later.

The absence of the flies/maggots would also tell you that whoever moved the body and dumped it could not have done so very long ago. Since the body has no maggots on it, it must have been dumped only a couple of hours before it was discovered.

Or, there may be signs that a particular insect has been feasting on the body. Say you find evidence that sand flies have been eating a body. Sand flies are found only on the beach. But the body was found in the mountains. Thus, the presence of sand flies would be a sign that the body had been killed on the beach, left there for several hours, and then moved to the mountains later and dumped there.