According to certain written records, "Put various bugs and snakes in a container and keep them in it until only a single living creature is left. That creature is called the 'undead insect'. It has the ability to confuse people and could be introduced through food or drink. It could do great harm to the victims."
The Miao people were experts in raising undead insects, which were called "grass ghosts" in the Miao language. Since the insect raisers were all female, they also went by the name "women of grass ghost".
The practice of raising undead insects was not part of the Taoist skills, but originated from the witchcraft culture, which was to some extent similar to the techniques of Mao Mountain. According to the customs of the Miao people, every village must have its own woman of grass ghost. However, with the passage of time, few successors of this skill remained.
The one of Baiqing Village was the only woman of grass ghost within a radius of a couple of hundred km.
These women had special status in their clans. On ordinary days, they were despised by their clansmen and excluded from every activity. However, when necessary, the clan had to turn to them for help.
As a result, they usually lived alone and developed unsociable and eccentric personalities. Those more perverse would release undead insects at people showing the slightest disrespect towards them.
The one Xiaozhai spotted, nonetheless, was a very pretty woman. Her long hair was coiled into a bun and she had eyes like flowing water when she stood by the stream and watched the wooden buildings from afar. She struck Xiaozhai as being odd because there was a frail and sickly look about her, as if she was possessed by something that was sucking her blood dry.
Long Tang apparently disliked her. Sticking her head out of the window, she shouted, "They're my guests. Go away!"
That woman was happy to see Long Tang's face, but was immediately upset by her words. She turned around and left without a word.
"She's my older sister. The woman of grass ghost took her away when she was five and she has been like this ever since. Anyway, stay away from her."
Long Tang spoke with a mixture of feelings, then went downstairs without another word.
After she left, Xiaozhai looked out of the window and suddenly giggled, "So, Brother Yu, what do you think?"
Gu Yu was greatly embarrassed. "Stop messing around!"
"I'm not! This is such a charming place, but not as charming as the Miao girls. Why don't you stay here and get married? I'll travel to the Western Regions and get the sacred texts on my own. By the time I come back, you'll probably have made a baby monk." 
He did not bother to talk back, but only thundered into the bathroom with a bag in hand. He mumbled, "I'm going to take a shower!"
'Such a boring man!'
Xiaozhai shrugged and leaned against the window pane, stretching out her long legs. Xiao Qing slipped out from hiding, slithering around on the ground happily, apparently very satisfied with the surroundings.
She looked around in boredom while playing with her pet.
Before they realized it, dusk had set in.
After dinner at Long Tang's house, they returned to their lodging. Evenings in Miao villages were dull. Basically, nightlife was non-existent. They chatted for a bit and went to sleep in their separate beds.
The cool, desolate moonlight lit the quiet room. Faint blue smoke was rising from the half-burnt Soothing Incense.
All of a sudden, the coiled-up Xiao Qing raised its upper body and slithered onto the window pane in spite of itself, as if drawn to some unknown attraction. Wrapping its tail around the handle, it pulled the window open slightly and went through the narrow gap in a swish.
It slithered its way through the wooden buildings, reached the ground outside, then swam across the stream and finally disappeared in the woods.
Deep inside the woods on an open space, that woman of grass ghost was heating up a bronze cauldron, which had a round body with a narrow opening and wide bottom. A campfire was strutted up under the cauldron.
In her clenched fist was some green powder, which she added continuously into the cauldron. Streaks of white mist kept rising out of the opening. Meanwhile, rustling sounds were coming from every direction of the woods. Countless black shadows wriggled in the moonlight, falling over one another to crawl into the bronze cauldron.
Among them were spiders, scorpions, small snakes, and centipedes, all of which were hideous and terrifying venomous creatures.
Seeing that the bronze cauldron was almost filled up, the woman's face brightened up. Soon afterwards, however, the joy turned into excruciating pain.
Her eyes were tightly shut as her body convulsed in pain. Underneath the fair skin of her face, something protruded in a wavy motion, as if a living thing was scurrying around.
"The all-mighty King Pan, I beseech your blessing. Help me…"
The woman gritted her teeth, streaks of blood oozing out of the corner of her mouth. With much difficulty, she pointed at the cauldron.
In that instant, as if the fire had grown more furious, the substance inside the cauldron started to sizzle and bubble. Together with the frantic hissing from the venomous creatures, the sound could chill one to their bones.
The hissings gradually ceased after quite some time and the woman did not look as pale as before. She pointed with her finger again and an indiscernible shadow flit across the air, then seemed to retreat into her body.
She panted and gasped for air, like someone who had escaped death by the skin of her teeth.
Right at that moment, another sound came from somewhere in the front, startling her. A small snake clad in emerald scales emerged. Our little fool had found this place following the scent, but arrived in time only to find the job already wrapped up.
It shook its head, apparently not happy with how things turned out.
The woman's face brightened up. Such a spiritual snake was very rare. If she could take it back and raise it, then put it inside the urn of undead insect at Duanwu [TL/N: the 5th day of the 5th lunar month] of the following year, the natural endowment of this spiritual snake would surely enable it to win out, which would make it into an excellent Undead Insect of Yin Snake.
The Undead Insect of Yin Snake would take its shape once inside the victim's body. It would take the form of either a snake or a soft-shelled turtle, which would then gnaw its way around inside the human body. This type of undead insect was worse at nighttime, when Yin Snakes would arrive with the wind and get access through the pores on one's body. With it, the victims were attacked from both inside and outside. It was pointless trying to find a cure.
Xiao Qing was used to its ostentatious manner backed by its master and had become ignorant of the real danger. It only saw the woman rise to her feet and smile at it.
The next second, it found itself flowing in the air—yes, flowing was exactly the word to describe it—and being drawn quickly towards her. Xiao Qing went frantic instantaneously, wiggling and waggling with all its effort, which was to no avail.
When it was close enough, the woman stretched out her hand to grab it when something flew near with a shrilling sound, ripping through the air.
A pebble hit the back of her hand. Xiao Qing fell to the ground and turned to run away at once.
"Sorry about that, but that snake is mine. You can't have it."
Two people came out of the woods along with the greeting—none other that the couple from the lodging. They walked to the middle of the clearing, exhibiting no malice, but only apparent curiosity.
"What was the thing you used just then? Was that a type of undead insect as well?" Gu Yu asked.
The woman frowned. Her red lips trembled slightly; she seemed to be mumbling something.
A solemn look suddenly crossed Gu Yu's face. Concentrating the energy in his palms, he grabbed at the air in front of him with his right hand, paused a little, then grabbed again.
It was unbelievable. He felt a slight prickle on his palm, like he had been stung by something. The invisible creature ran into a brick wall with him and turned to dash at Xiaozhai. Flipping her fingers, Xiaozhai twirled her shiny dagger in the air and held it in front of her.
The sound reminded one of a roaring dragon, which disturbed the night sky.
The woman went pale with terror—these two people could fend off her undead insect. She was about to strike again with all her effort when she heard someone calling her name.
So, the woods turned out to be a popular spot for tonight, which was receiving its third group of visitors now. The shuffling footsteps approached them quickly and a whole bunch of people appeared all at once, with Long Tang on the lead. Behind her were two young men and on the back of one of them lay a boy.
"Brother Yu, Sister Xiaozhai, why are you…"
The scene took Long Tang by surprise. She then said angrily, "Long Qiu, you're hurting people again!"
"No, I didn't…"
The woman seemed to be very tolerant towards her. The aggressiveness from earlier was nowhere to be found as she denied in a flurry with hers hands waving around.
"Don't lie! I see your cauldron right there!"
"She's telling the truth. We couldn't sleep and decided to take a walk. We only ran into her by accident." Gu Yu came to Long Qiu's rescue.
Long Tang only stopped accusing her then. She darted a despising look at the cauldron and said, "Xiao Shan has a tummy ache. Have a look."
Long Qiu lowered her head and came up to them. She let the boy lie flat on his back and touched his abdomen. "When did the ache begin?"
"He was fine at dinner, but woke up in the middle of the night saying his tummy ached. We took him to you right away," replied a man.
"It's probably something unclean he ate. Follow me."
With that, she led the crowd deeper into the woods and stopped outside a wooden house. The others dared not move any closer. She entered alone and came out moments later with a raw egg and a red thread.
Long Qiu tied the thread around the egg, then sliced her sharp fingernail across the fair, tender skin of her forearm. Blood droplets oozed out. After that, she let the blood trickle onto the egg. The dark red droplets slipped down the egg shell, being gradually absorbed by the red thread.
This went on for a little while before she lifted up the boy's top and rolled the egg on his abdomen.
The crowd all had funny looks, which were a mixture of fear and anticipation. Gu Yu and Xiaozhai watched the process, forgetting to blink. They found it a fascinating and novel practice. The energy involved belonged to another system, something utterly different from the Taoist one.
A couple of minutes later, Long Qiu asked, "Is the tummy ache gone?"
"Yes," answered the boy, lifting his little face.
"Hehe, remember, from now on, don't…"
"Aiya, that's great, very nice. Come, let's go back to bed. Thank you for that!"
Before Long Qiu had a chance to finish her sentence, the man held up the child and threw out the words in a hurry, as if he was to run for his life. Long Tang also came up to them and said, "Brother Yu, let's go. Everything is sorted out here."
Neither of the two moved, which puzzled Long Tang. Xiaozhai turned around at this moment with a grin. "That egg of yours, may I have it?"
Long Qiu looked up, a hint of surprise flashed across her dispirited face. Before knowing it, she was handing Xiaozhai the egg.
Xiaozhai smiled at her, then rose to her feet and left.
They had no desire to go back to sleep now. After they left the woods and returned to their rooms, Long Tang could not hold back her complaints any more. "Why did you take that? It's unclean."
"In what sense do you mean by 'unclean'?"
It's, it's… aiya, don't break it!"
Seeing Xiaozhai break the eggshell with a knock, she scuttled to the other side of the room and dared not watch it.
The two found her behavior peculiar. The egg fell into the cup with a clatter and they moved closer to look. There was nothing wrong with the egg white. The egg yolk, on the hand, was not yellow anymore, but a lump of white substance.
Even they found it gross. It was a pile of wriggling white worms.
"Are these undead insects?" Xiaozhai was curious.
"Not exactly. They are actually, em…"
Long Tang tried to find the right words. "They are actually the energy making people sick, which has been expelled by the undead insect. Yes, that's what they are."
The two winced. It was fascinating. That sickening energy could be materialized into actual thin white worms. Gu Yu blinked and chuckled, "If you are not in a hurry to get home, stay for a while and tell us about it. We're very interested in that."
"Sure, I'm not really sleepy anyway."
Since Gu Yu himself had invited her to stay, naturally she would not say no to that. She went on, "Actually, I don't know much about it either. All I know is that there are many kinds of undead insects. Some can hurt people and some can save lives. There used to be a woman of grass ghost in every village, but nobody wants to learn the stuff anymore. Long Qiu is probably the last one."
She was a little upset when Long Qiu's name was mentioned. Her voice lowered. "We used to have one of those women in our village, a very old woman. She was afraid of the stuff going uninherited and went to talk to uncle. He let her pick a pupil from five villages and sister became the chosen one… she was not always like this…"
 TL/N: Xiaozhai is teasing Gu Yu with a plot taken from the book "Journey to the West", or "西游记", which is also known by the title "Monkey". In it, Sun Wukong, the monkey and the most powerful disciple of Tang Sanzang (the monk, the master, and the nominal main character) would joke about leaving the master behind with some covetous female character to get married and have "little monks".