Because I'm not sure myself:
The ground opened in the year 135. A few of the bugs spewed forth in the middle of one of our larger cities. Black and scaly. They emitted darkness. A brief encounter with our average populace lead to an encounter with the police... which turned violent. The bugs retreated back underground... taking with them a woman and her child. The city's SWAT team went to the rescue. They brought back the civilians; but left three of their own behind dead. They had stumbled into the first nest. The Army was called up. They entered into the tunnels(already nicknamed the devil's sewers). It was dark dark in there. Damp wet tunnels about 5-10 meters wide. The Army brought light and flame. They found a HUGE nest at least 10 miles by 10 miles by 5 miles.
There was a fight, you could almost call it a battle. Millions of bugs vs thousands of troops. No heavy bombs... the nest was directly beneath a city. So everything had to be small. Fire bombs, flamethrowers, shotguns and bayonets. The wet black scaled bugs lost. Completely defeated. Chased down tunnels. Not that it was easy. The tunnel fighting was fast and deadly... bugs don't have weapons but claws in the dark work just as well. And they are cunning as hell.
The army found a maze of tunnels. Large ones(25m radius), small ones(5 m radius). All smooth bored and well traveled. The large ones led to more nests just as big. Everywhere the bugs.
We found edible plants and it turns out that roasted the bugs themselves made a really good meal. This is what started it all. You see topside we'd just had another global war. Food was scarce... really scarce. If you had a working farm you were a king. So news of a new food supply, especially one as vast as this was welcome. The army expanded a cleared area and engineers set up what would becomeDownbase 1. Once the base was established the government created a bounty system and the first civilian hunting teams were allowed down. The bug-business exploded.
Soon after several more deepground cities were established. Humanity began to live downside.
In general the bugs are easy hunting. However they can and do form killing swarms on occasion and these swarms will take out even a large hunting party if you are not always on your guard. Don't think that just because they die to a single shotgun blast or knife thrust that they can't kill you. They've gotten their fair share of the kills since we moved down here.
Also I'm warning you now, watch out for the ones with the almost maroon stripes on their back legs. They have this thing they do. They spit something at you and if it lands it has a paralyzing affect that leads to an altered mental state. Your body will move of its own accord and will defend the bug. You'll shoot teammates or civilians and have no control over it. Even mates you've hunted with for years. Thewhitecoats (scientists) have no clue why or how this occurs but it is well documented and it can happen to anyone they get close to. I know. Oh I really know.
I came down here back in '39. Right after the first teams were loosed. Back when Davison and Gyuen were just starting. My team wanted to make a name for itself. Find the next big nest. We started down-north and just kept walking. About three weeks in, we started seeing our first bugs. We'd bagged a good even two or three hundred(about 20 each or so) and were just getting ready to head back when we encountered the swarm. I swear it moved tactically. We were hit from three sides by it. Juan died to a panicked shotgun blast. Someone threw a fire apple and the room erupted in flame. I sprinted for a side tunnel. The swarm was still light blind and I got out. I kept running. Panic does that... makes you forget your mates and just run. I had a full load of ammo too. Sucks.
I ran out of light after about a mile. Went reaching for my pack to get a flare out and just as I lit it I saw something black twitch and tab something sticky hit my head. The world slowed down. I felt my knees give way and everything went black. Something carried me for a while. Then something carved out my right eye. Goo filled it. Suddenly I could see again. Oddly but I could see. Too bad I couldn't move.
I was in a bug den. There were three bugs there. Two with orange stripes and one with maroon. The maroon striped one(I decided to call it MaroonOne )... it twitched and my body stood up. The next week was spent with me walking around to its twitches. Every time it would put me back out and I'd wake up with a new headache.
My vision got a little bit better and then after a bit more of me walking around I was lead out of the den. There were a bunch of other humans there. Three of them my mates. MaroonOne twitched some more. My hand came up and drew my knife. I freaked out. Ever have those dreams where you can't move? Exactly like that. MaroonOne twitched. I stabbed. She(it was a female) twitched again. I stabbed some more. The entire time I'm screaming and sobbing inside. That still makes me want to throw up. I guess I'll be okay. The psychs say that I should talk about it to keep stable.
There were some bugs there as well. The sticky goo that was holding the humans was holding them too. More twitching. More stabbing. That was the last time there were humans that I remember. Well not the last but that was a LOT later. After that it was just other bugs. Green stripes, yellow stripes, maroon stripes(only a few).
I got to know the nest real well. I would be led places and then my body would come back later to stab. I didn't even have to be in sight ofMaroonOne ... just a bunch of twitches and then off I'd go. When I was allowed to sleep I was fed the ones I stabbed, I was able to drink the tunnel water. This went on for ages and ages.
It was in the second push. The one that the army made to setup the lower cities? A squad hit the nest I was being kept in. I woke up to twitching and my body walked me out and headed right at the soldiers. I was told later that I looked like a zombie. They didn't want to shoot me, thankfully; but I was surrounded by red stripes and charging right towards their position. So someone through a fire apple right at my feet. The flames hurt oh they hurt like hell. But they burnt whatever was on my head. For the first time I could move. I screamed. I fell to my knees screaming and yelling and laughing.
The red stripes just burnt and died. The medics got to me before I could die of burns. A new skin patch fixed almost all the damage that the fire apple had caused. A brief debriefing put me in the psych's hands. After two years of mental rehab I was released. Free to be human again. The year? '47. But what I could tell them about bugs... more than anyone alive. Others have been taken by maroon stripes. None as long as I. Usually they were found dissected in bug dens. A few were twitch walked like me. Most were recovered dead after they attacked humans. I don't know of anyone who was recovered and rehabbed like I was. I go to the chapel daily and thank God for my luck.
You know they only recovered three maroon stripes when they picked through the bug bodies afterwards? And none of them had a single stripe. All of them had double or triple stripes. That is why I don't go back out there. That is why I teach. Because She might still be waiting. Twitching for my body to dance.