Chapter 964 Chapter 964 Something is wrong with the insects too
It is relatively simple to distinguish the third instar larvae. Because this is the last step for the larvae to become adults, its size has become very large and can be seen clearly. Once it reaches its shape, it can turn 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 China's traditional Chinese medicine industry. Traditional Chinese medicine uses "grain bugs" as medicine, and its main treatment is "strengthening the spleen and eliminating accumulation; clearing away heat". Special attention should be paid here. Some of today's Medicinal material dealers also use the larvae of other flies for medicine. Because ordinary people do not know how to do it, they can easily be passed off as inferior. Especially when medicines are directly ground, crushed grain insects, even if the goods are not correct, are There is nowhere to complain.
Therefore, if you can’t catch grain bugs yourself and don’t want to be deceived, you can first go to the dry toilet to observe and learn. There are only a few provinces in China that lack the distribution of big-headed golden flies, mainly Heilongjiang and Kyrgyzstan. , and Qingxi Xinsan Province, and other places are easy to find.
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 the help of Wanbaoming, Jiang Yuan quickly began to screen eggs and eggs again.
A fly undergoes a complete metamorphosis - it goes from egg to larvae, then from larvae to adult, and each time it undergoes complete metamorphosis, that is, it completely changes into a completely different form.
This gives each form of the fly a special look, making it easy to identify them—it can only be said to be easy.
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 hasn't seen them either. Such.
Normally, if you want to carry out such a detailed classification and classify specific varieties, you will actually need 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, opened the cork and smelled a strong smell.
The stench was immediately 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, put them in a bottle and bring them back. In addition to bugs and eggs, many bottles will inevitably contain some Corpse water and the like.
At that time, I didn't realize that it was masked by a 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 the labels and stick them one by one.
In addition, there are more insects that do not belong to 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 of flies is relatively It's clear. It hatches every few days and grows up every few days. I can't say exactly, but there is a pattern.
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, then the deceased has been dead for about 20 days. If the insect that has been dead for longer can still be the second and third generation insects, just add up 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. This does not waste time at all, nor does it waste the time of the forensic doctor.
But——————Jiang Yuan’s feelings about these insects are not so clear.
Wan Baoming asked: "The body we found was at the second scene. Did the two scenes interfere with 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 not the second one." It’s the third scene.”
"Ah?" Wan Baoming was stunned: "The third scene? The body parts were moved twice? Why?"
