Ant Nectar

 is a chem naturally produced by giant ants.

Fallout 3
It is relatively rare since it is only found on few giant ants or in Ant Refuse Piles. A few can be found on the dead body of William Brandice in the Marigold Metro Station. It can also be found by going to Shalebridge and searching the large mound in the same room that you find the Large Ant Egg Pile and the Ant Researcher, and checking the mound every few in game days.

Fallout: New Vegas
In Fallout: New Vegas, Ant Nectar is most commonly found in Ant Refuse piles or on dead ants. If taken in excess, you can get addicted to it. Unfortunately, its addiction appears to be uncureable. Neither Doctor Michell in Goodsprings nor Julie Farkas in The followers of the Apocalypse camp in Freeside have been able to cure it.