entomologist:
(plural: ‘entomologists‘ — for the right pronunciation, please click here)
a person/zoologist who studies insects scientifically, and so knows much about insects, their structure, life-cycle and habitats,

two entomologists with their nets on a field study
Though entomologists are not very well known to the general public, their studies and analyses are very important and useful in controlling pests that damage crops, damage buildings and harm the people.
Some entomologists, known as forensic entomologists, help the police in crimes in deciding when a person is killed by the studying the larvae of the insects found in the dead body, and their testimony is accepted in the court of law!
Entomologists also help governments and/or agricultural experts regarding the effects, good or bad, of using pesticides in a vast area in general and on some useful insects and other creatures in that area in particular.

two entomologists doing an experiment
