Entomologists are precious back up assistants for the legal system. Knowledge of insects can in effect lead to the discovery of the exact moment death occurred, and, in certain cases, to the murderer being identified. But, if we want to understand this ‘forensic entomology’ better, it is a good idea to forget the simplifications of popular TV series.

Up until the seventeenth century, it was believed that the source of maggots on a body was the body itself. It was only in 1668 that a certain Fransisco Redi showed that the larvae came from eggs deposited by flies. More than three hundred years later we are finally beginning to understand a little better the role of insects in a body’s decomposition, and, through this knowledge, to measure to what extent these ‘garbage collectors’ can help to place the date – or even the hour – of the death of a living organism. And, in certain cases, to expose the murderer.

When death occurs, the body right away attracts a certain number of insects (and even fish if the body is in an aquatic environment – Useful Reading) through ‘smells’ or volatile organic compounds released by the mortal remains. The quickest to stream towards them, if both temperature and accessibility conditions are met, are the Calliphoridae (or carrion flies), a family of the Diptera order. Amongst them we can include the bluebottle (Calliphora vicina), as well as the Sarcophagidae, such as the flesh fly (Sarcophaga carnaria) or the greenbottle (Lucilia sericata). One of the characteristics of these Diptera insects is that they have a holometabolous development life cycle, which means that the larvae are morphologically and ecologically different from the adults.

(1) Forensic entomology is divided into three branches: forensics (the subject here), urbanism (it for example studies cockroach invasions in homes) and the food industry (it looks into the threats faced by perishable goods).