Entomologist
An entomologist was an expert on insects. (PROSE: The Slender-Fingered Cats of Bubastis)
UNIT had an entomologist assigned to the victim-retrieval station in Hereford. Martha Jones suggested that she might be able to explain why the maggots inside of the chameleon were so advanced. (AUDIO: Dissected) After Sergeant Brundle was infected by a Wirrn egg, Shana Siddiqui was hired as UNIT's entomologist to try to find a cure. (AUDIO: Hosts of the Wirrn)
Star Seasons advertised for an entomologist, but misspelt it as "etymologist" and ended up hiring Professor Bil Bil Gloap rather than admit their blunder. (PROSE: The Slender-Fingered Cats of Bubastis)