Coleopterist
A person who collects beetles is a coleopterist.
hemipterologist
A scientist who studies insects is an entomologist. An entomologist who specifically studies beetles is a coleopterist.
A geologist is a person who studies rocks and rock formations. A rock collector or a rock hound is a person who collects rocks for fun.
arthropologist
If you mean "who studies beetles," then the answer is an entomologist (person who studies insects.)
A person who collects nests or eggs and studies them is called an oologist.
That's an entomologist.
That person would be called an antiquarian or a collector of antiques. They are interested in studying and preserving items from the past for historical or cultural purposes.
A philatelist is a person who collects stamps and can also be referred to as a lover of stamps.
People that do this are called "rockhounds".
a person who studies and collects mollusc shells as a profession or hobby paula