National Forensic Doctor

It is relatively simple to distinguish third instar larvae. Because this is the last step for the larva to become an adult. Its size has become very large, and its appearance can be clearly seen. It can then transform into a fly.

Therefore, sometimes what emerges from the cocoon is not necessarily a butterfly, but a moth or a fly.

Under Jiang Yuan's guidance, Wan Baoming quickly became familiar with several common third-instar larvae.

When it comes to practicing biology, I learn it very quickly. When I read books and pictures in school, I can’t always remember the eighth and ninth abdominal segments.

But if you see it for real, see it a few times, and compare it a few times, your brain will remember it very quickly.

For example, the most common maggots in dry toilets are long cylindrical, somewhat flat, with a pointed tail, and a slightly transparent surface with a slight yellow tint. It is the big-headed maggot of the family Calliphoridae. Fly, scientific name (Chrysomyiamegacephala

Fabricius)

The golden-headed golden fly is also the most common necrophilic fly, especially in places with many dry latrines. Whenever a corpse appears, the golden-headed golden fly will fly over and lay eggs, thus becoming a good helper for forensic doctors.

Big-headed golden fly not only helps forensic doctors, but also helps my country's traditional Chinese medicine industry. Traditional Chinese medicine uses "grain bugs" as medicine, and its main treatments are "strengthening the spleen and eliminating accumulation; clearing away heat". It is also important to note here that some medicinal dealers today also use the larvae of other flies as medicine. Because ordinary people are not knowledgeable, they can easily be passed off as inferior products. Especially now that medicines are directly ground, even if the crushed grain insects are not delivered correctly, there is no way to complain.

Therefore, if you can't catch the "grain bugs" yourself and don't want to be deceived, you can first observe and learn in the dry toilet. There are only a few provinces in China that lack the distribution of Big-headed Golden Fly, mainly Heilongjiang and Jilin provinces, and Qingxi and Xinjiang provinces. It is easy to find in other places.

For people in these places, if they really don’t know how to tell the difference, they can compare it with the calf of a ballet dancer. The shape and appearance are basically the same, which shows that beauty and ugliness in the world do have something in common.

With Wanbaoming's help, Jiang Yuan quickly began to screen eggs again.

A fly undergoes a complete metamorphosis—it develops from egg to larvae, then from larvae to adults, and each time it undergoes complete metamorphosis, that is, it completely changes into a completely different form.

This gives each form of flies a special appearance, and it can only be said that it is not difficult to identify them.

Despite this, Wan Baoming's eyes widened when Jiang Yuan began to sort the fly eggs.

"Can you really tell who laid the eggs just by looking at them?" Wan Baoming has also seen and eaten them - "-or to put it another way, he has worked with the big guys in entomology, and he has never seen them. Such.

Normally, if you want to carry out such a detailed classification, when classifying into specific varieties, you actually have to check reference books.

For example, "Fauna of China", "Economic Insects of China", "Key List of Common Flies in China", etc.

This is like writing experts who also need "Shuowen Jiezi" and "Kangxi Dictionary".

Jiang Yuan didn't need to explain too much to Wan Baoming. He just smiled and said: "You can't tell it at just one glance. Sometimes you have to look a few times -

Mu Zhiyang couldn't help but look up at Jiang Yuan: "Captain Jiang, you look a little humorous when you look at the fly eggs."

Jiang Yuan smiled and said without raising his head: "Put on some more gloves and help me remove all the bug eggs from these bottles and place them on the glass plate so that I can identify them later. "

Mu Zhiyang said "Oh", put on his gloves, took out a bottle designated by Jiang Yuan, and smelled a strong smell when he opened the cork.

The stench was sucked away by the ventilation device above his head, leaving Mu Zhiyang to take a full breath.

The on-site survey personnel will not be able to distinguish the types of these insects in detail. In the final analysis, they just save a spoonful, poison them to death, put them in a bottle and bring them back. In addition to bugs and eggs, many bottles inevitably contain some corpse water and the like.

At that time, I didn't realize that it was masked by the stronger smell at the scene. But when I smelled it again in the laboratory, I felt very addictive.

Soon, the black leather test bench was filled with the bodies of various maggots, and the eggs, which were only millimeters in size, were also placed in disposable plastic petri dishes, arranged neatly one by one.

Mu Zhiyang continued to write labels and stick them one by one.

In addition, there are more insects that are not flies and insect larvae and eggs.

These are all trivial and detailed tasks, but only if they are done carefully can it be the turn to judge the time of death.

In fact, the main work is to identify the types of eggs, larvae, and adults. The remaining work is theoretically not much, as long as you follow the steps...

"There's something wrong with these bugs." Jiang Yuan stopped after looking at them.

"Something's wrong with the bugs?" Wan Baoming didn't realize what was going on for a while.

Jiang Yuan said "Yes" and then looked at the record he made and thought about it.

The technicians in the room subconsciously stopped when they heard the conversation between the two.

Many operations are lossy operations. If you are not in a hurry, it is always right to wait.

Jiang Yuan sat down to himself, studied for a while with his pen, then looked at Wan Baoming, and said: "Looking over now, I feel that what I see are not flies of the same origin, not one group, not two groups -"

Generally speaking, after a corpse appears, nearby flies will come to lay eggs as fast as possible. This fastest speed is often measured in seconds. In addition, the generation lineage of flies is relatively clear. It hatches every few days and grows up every few days. It cannot be said accurately, but it is more or less consistent.

Forensic entomology determines the time of death based on the reproduction and growth of insects.

For example, it takes about 20 days for an insect to grow to the third instar, so the deceased has been dead for about 20 days. If the bugs that have been dead for longer can still be the second and third generation bugs, just superimpose the time and calculate it.

There is another piece of trivia here. Adult flies usually emerge from their cocoons and begin to reproduce within a few hours. It doesn't waste any time at all, nor does it delay the forensic doctor's time calculation.

But——————The feeling given to Jiang Yuan by these insects is not so clear.

Wan Baoming asked: "The body we found was at the second scene. Did the two scenes interfere with the time or something?"

"It must be interference. The problem is, judging from the current situation of flies-" Jiang Yuan said this, clicked on the record book, and said: "In my judgment, the scene we discovered is no longer the second one." It's the third scene."

"Ah?" Wan Baoming was stunned: "The third scene? The body parts were moved twice? Why?"