A scientist whose field of specialisation is diffrent species of insects?

Georges Brossard: http://www2.ville.montreal.qc.ca/insecta...

As noted, the general answer is an entomologist. A wonderful example and one of the few famous scientists who started in that field is E.O.Wilson. He%26#039;s got a ton of books and they%26#039;ll all great reading and very informative. He%26#039;s into far more than insects now, and his insight at this point in time is invaluable.