Chapter 964 The Worm Is Also Wrong
It is relatively easy to distinguish the third instar larvae. Because this is the last step for the larvae to become adults, its body has become very large, and its appearance can be clearly seen. Then it can transform into a fly.
So, sometimes the cocoon is not necessarily a butterfly, it may be a moth or a fly.
Under Jiang Yuan's guidance, Wan Baoming quickly became familiar with several common third instar larvae.
Biology is learned very quickly when it is put into practice. When reading books and pictures in school, I always remember things like the eighth and ninth abdominal segments.
But if you see the real thing, 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 cylindrical and slightly flat, with pointed tails, slightly transparent on the surface, and slightly yellow maggots. They are the big-headed golden flies of the family Calliphoridae, with the scientific name (Chrysomyiamegacephala
Fabricius)
The big-headed golden flies are also the most common necrophilic flies, especially in places with many dry toilets. Whenever there is a corpse, there will be big-headed golden flies flying over to lay eggs, thus becoming a good helper for forensic doctors.
The big-headed golden flies can not only help forensic doctors, but also help my country's traditional Chinese medicine industry. Traditional Chinese medicine uses "grain worms" as medicine, mainly for "strengthening the spleen and eliminating accumulation; clearing heat and removing". It should be noted here that some herbal medicine merchants nowadays also use the larvae of other flies as medicine, because ordinary people do not understand the business, and it is easy to be sold as inferior. Especially at the moment when medicines are directly ground, the crushed grain worms, even if the goods are not the same as the board, have nowhere to complain.
Therefore, if you can't catch the "grain bugs" when you really need them, and you 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 flies, mainly in Heilongjiang and Jilin, and Qinghai, Xi'an and Xinjiang. It is easy to find them in other places.
For people in these places, if they really don't know how to distinguish them, they can compare them with the calves of ballet dancers. The shapes and appearances are basically the same, which shows that beauty and ugliness in the world are indeed connected.
With Wan Baoming's help, Jiang Yuan quickly began to screen eggs and.
Flies are a kind of complete metamorphosis-it develops from eggs to larvae, then from larvae to, and then from to adults, each time it is a complete metamorphosis, that is, it completely changes into another appearance.
This makes each form of flies have a special appearance, and it is easy to identify-it can only be said that it is not difficult for those who know how to do it.
Despite this, when Jiang Yuan began to classify the eggs of flies, Wan Baoming still widened his eyes.
"Can you really tell who laid the eggs just by looking at them?" Wan Baoming had seen and eaten them before ---"- or to put it another way, he had worked with the big guys in entomology, but he had never seen anything like this.
Normal big guys, if they want to do such detailed classification, when they classify specific species, they actually have to look up reference books,
such as "Fauna Sinica", "Chinese Economic Insects", "Chinese Common Flies Index", etc.
It's like an expert in writing, who also needs "Shuowen Jiezi" and "Kangxi Dictionary".
Jiang Yuan, however There was no need to explain too much to Wan Baoming. He just smiled and said, "You can't tell it with just one look. Sometimes you have to look at it a few more times-
Mu Zhiyang couldn't help but look up at Jiang Yuan: "Captain Jiang, you are a little humorous when you look at the fly eggs. "
Jiang Yuan smiled and said without looking up: "Please put on another pair of gloves and help me clear all the insects and eggs in these bottles and put them on the glass plate so that I can identify them later. "
Mu Zhiyang said "Oh", put on gloves, took a bottle designated by Jiang Yuan, and smelled a strong odor when he opened the bottle stopper.
The odor was sucked away by the ventilation device above his head, and Mu Zhiyang just breathed it in.
The on-site investigators will not distinguish the types of these insects in detail. In the final analysis, they just keep a spoonful and put the poisoned ones in the bottles and bring them back. In addition to insects and eggs, many bottles will inevitably contain some corpse water.
At the time, I didn't feel it because the smell was more intense at the scene, but when I returned to the laboratory and smelled it again, I was very addicted.
Not long after, the black leather test bench was filled with the bodies of various maggots. The millimeter-sized eggs were also placed in disposable plastic culture dishes, neatly arranged one by one.
Mu Zhiyang accompanied him to write labels and stick them one by one.
In addition, there were more insects that did not belong to flies and insect larvae and eggs.
These were all trivial and delicate work, but only by doing them carefully could we get to the stage of judging the time of death.
In fact, the main work was to identify the types of eggs, larvae, and adults. The remaining work, in theory, was not much, as long as it was done step by step...
"These insects are not right." Jiang Yuan stopped after watching.
"The insects are not right?" Wan Baoming didn't realize what was going on for a while.
Jiang Yuan said "yeah", and then looked at the records he made and thought.
The technicians in the room heard the conversation between the two and stopped subconsciously.
Many operations are destructive operations. If you are not in a hurry, it is always better to wait.
Jiang Yuan sat down by himself, studied it with a pen, looked at Wan Baoming, and said: "Yi now looks at it, and it feels that what I see is not a group of flies of the same lineage, not one group, nor two groups-"
Generally speaking, after a corpse appears, nearby flies will come to lay eggs at the fastest speed. This fastest speed is often measured in seconds. In addition, the generation of flies is relatively clear. They hatch every few days and grow up every few days. It cannot be said to be accurate, but there is a spectrum.
Forensic entomology is to judge the time of death based on the reproduction and growth of insects.
For example, it takes about 20 days to grow to the third instar, so the deceased has been dead for about 20 days. If the dead longer can be the second or third generation of insects, just add up the time and calculate it.
There is also a little-known fact here. The adult flies usually emerge from the cocoon and start to reproduce a few hours later. It does not delay the time calculation of the forensic doctor at all.
However————--The feeling that this batch of insects gave Jiang Yuan was 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 definitely interfered. The problem is, judging from the current situation of the flies—" Jiang Yuan said here, pointed at the notebook, and said: "In my opinion, the scene we found is no longer the second scene, but the third scene."
"Ah?" Wan Baoming was stunned: "The third scene? The body parts were moved twice? Why?"