Fallout 3/Those!

Fire ants are attacking Greyditch, just in the outskirts of the DC ruins.

Initially, Bryan Wilks will run up to you in a panic, about the ants taking his father. You can talk to him to get some more information, and with the appropriate perks or abilities, you can get information about the location of useful items (such as a dumpster behind the diner).

Wilks residence
Bryan Wilks' father was already dead, with two dead fire ants in the house. However, you can get a shack key from the body, and collect information on Dr. Lesko.

The other residences don't contain too many items of interest, but Brandice's House has a timeline of what happened.

Marygold Station
AS you can determine from the nearby shack, Marigold station seems to be the location of importance.

Dr. Lesko
Dr. Lesko was intended to reduce the size and threat of the ants by injecting FEV mutagens into the eggs, but made a mistake in doing so. Instead, he caused the ants to breathe fire rather than become smaller.

He wants to keep the Queen alive, and asks you to kill the nest guardians to give him access to the terminal.

Dr. Lesko is a good character. If you complete what he asks to do, he will hive you either the Ant Might or Ant Sight perk, which boosts Strength or Perception by 1 point, and gives you a 25% resistance to fire.

Grady's Last Recording
In the metro station, you can find a recording about the naughty nightwear. The key for the safe is in the firehose in a closet, and the safe is in a room with three spinning lights (north of the Dr. Lesko's lab.)

When you get the Naughty Nightwear, Lug-Nut will come and demand you give it to him. A speech check can be used to get rid of him, but you can use other means of dealing with him.

Bring this to Ronald Lauren in Girdershade.

Bryan Wilks
When you return to Bryan Wilks, he will mention that the ants all killed each other. However, he will need a new home. He suggests contacting Vera in Rivet City, she is the owner of the Hotel within the city.

You get a Karma boost for telling Vera about Bryan.