Ant queen pheromones

Ant queen pheromones are very strong aphrodisiacs that increase the user's Charisma at the cost of Intelligence and Perception. Because they are so rare and have large penalties, it makes more sense just to either collect or sell them.

If the player needs to increase his/her Charisma in Fallout 3 for any reason, Grape Mentats (which give +5 to Charisma with no negative effects) that are found in the National Archives (up to seven are obtainable if the player finds the vouchers in the foreman's office and completes the quiz) are a much more sensible substitute.

Fallout 3

 * Giant ant queen corpses (there are three giant ant queens: one in Marigold Metro Station, one in Shalebridge, and one in the Corvega Factory).
 * Cindy Cantelli at A Quick Fix in the Rivet City marketplace.
 * There are, in total, four ant queen pheromones in the Capital Wasteland.

Fallout: New Vegas

 * Ant Mound, can sometimes be dropped by the fire ant queen in the tunnels under the barn.

Related quests
Fallout 3:
 * A Nice Day for a Right Wedding: Angela Staley wants ant queen pheromones to help her seduce the acolyte Diego.