Entomologist/Fallout 3

Entomologist is a perk in Fallout 3 and Fallout: New Vegas.

Fallout 3
With this perk, you inflict 50% more damage when attacking every radroach, bloatfly, giant ant, fire ant and radscorpion. This perk also allows for expanded dialogue options when speaking with other entomologists, especially in the quest "Those!".

Fallout: New Vegas
With this perk, you inflict 50% more damage when attacking every cazador, radscorpion, radroach, giant ant, mantis and bloatfly.

Behind the scenes

 * Radscorpions are technically classified as arachnids, rather than insects, but the scientific field of entomology is limited to just insects.