Text written in Basque and translated automatically by Elia without any subsequent editing. SEE ORIGINAL

Insects from the corpses

When we find dead animals in the mountains, they are usually in the process of decomposition. And this process involves hundreds of families of insects. They smell the slaughter miles away and go for food. They are also organized in a very special way: in the dead body of the animal the insects form a defined ecosystem and respect the order between them in this feeding process. Many of us do not like them very much, but thanks to the work they do, among other things, they reduce the risk of spreading diseases. In the Department of Forensic Entomology of the University of the Basque Country, the corpses of animals are studied. By studying the insect larvae present in them, they can find out when the animals have died.

Is there life after death? Yes, necrophagous insects bear witness to this. Their food is usually corpses and organic matter. Like a CSI episode, these white-clad friends will take advantage of these insects to find out how long the ankle corpses have been in the forest. They are students of the master’s degree in forensic analysis taught by the University of the Basque Country and today it is the turn of entomology. They will work as in the TV series, or rather, the CSI works as they do.

MARTA SALOÑA, forensic entomologist, UPV/EHU: Yeah, it's close to reality. They have a forensic entomologist as their advisor and often start from real cases that have actually occurred and been published. However, since they are a series of cinematographies, what you see is not always reality.

A corpse is a defined ecosystem. Its decomposition follows a certain order, which is called ecological succession. I mean, there's shifts, and everyone respects them, too. From a distance, they smell the body from miles away. Up to 100 species could participate in the process.

MARTA SALOÑA, forensic entomologist, UPV/EHU: Some species are pioneers, followed by others that not only adapt to the new situation but also change it. The Californians first arrive at the corpses. According to the season of the year there are usually different species, but the most abundant is the Calliphora vicina, the famous blue fly, with which another family of flies, sarcophagids, ripens and ripens. According to their names, they live in the vicinity of the tombs, among the corpses.

You have to be careful with them. Blue flies place the larvae, but they are thrown by sarcophagids, which can penetrate through the holes in the mouth, nose or ear, causing myasis. That is, the larvae could use our body, our living flesh, as food.

MARTA SALOÑA, forensic entomologist, UPV/EHU: Since they are launched, it is possible that the larvae of sarcophagids are more developed than those of californians, so it is necessary to be careful not to make mistakes. Beetles come to eat larvae and eggs; if they eat everything, it seems that no flies have ever come; it is necessary to know that this can happen. At the same time, wasps are also exposed, they put eggs inside the larvae, so we can find no flies but wasps. And we also found mites.

The samples are processed in the laboratory. That's when the insects start showing information. Californians and their larvae are the most abundant and also the most informative. The larvae are first cooked for conservation and because they are easier to measure in the long run. The size is an important fact. Larvae do not always grow in the same way: the size of the larvae depends on the temperature. That is why, in real cases, when a corpse is found, a thermometer is placed at the scene.

MARTA SALOÑA, forensic entomologist, UPV/EHU: Data are collected on five days and compared to the nearest weather station. Then, the delay calculation is performed. If the scene and station data match, we can use the station data.

That is, if the data from the thermometer and the station match, we can go back in time and find out the temperature at which the larvae have grown, that is, how many days or hours it has taken the larvae to reach the size they have now, that is, since when the body is there.

But it's not that easy. How do we know how much a larva grows at a certain temperature? With the test done. Marta Saloña’s team has been working on this task for five years. They have been making growth charts of various species of the Californian family. This is an indispensable database to be used in cases that occur in the environment, since until now external information was used: From Austria, England, Russia. And the weather is not the same, not even the flies. There's information there now.

MARTA SALOÑA, forensic entomologist, UPV/EHU: The temperature we measured was about 20°C, so we would use a growth graph corresponding to this temperature. According to this, we can guess the age of larvae with an error of a few hours or a day.

This work is accompanied by a map of the two most abundant flies. Where and how Calliphora vicina and Calliphora vomitoria, blue-green flies that we all know, are distributed. One is urban and the other prefers the countryside. Maps for what? With this information, it is possible to know if a corpse has changed place or in which environment it was killed. The work of forensic entomologist Maite Gil can also help to deepen the investigation. DNA from eight species of the Californian family is being separated.

MAITE GIL, PhD candidate in forensic entomology, UPV/EHU: Morphological identification is difficult when the animals are immature or only a part is found, such as no larvae and a pupa or puppet. Then you could identify it by DNA.

MARTA SALOÑA, forensic entomologist, UPV/EHU : And that is a family. In the Basque Country there are between 20 and 30 families of flies that are found in the corpses and we hardly know anything about them. This shows how little we know and how much work remains to be done.

Students continue to work on measuring and identifying larvae. It's just starting, it'll be two weeks to find out. On TV, they solve cases faster, for some reason it's fiction.

AILANDER URTIAGA, student UPV/EHU: Everything seems easier on TV. This is hard, we're working with animals and animals are chaos. There are three important phases in the life of a fly: larva, pupa and adult. We have only found larvae, no pupae, so we can deduce something approximate with it.

You have to stop not knowing when the orchestra died or who the murderer was!