Insects are ecologically and economically important and are either the bane or boon to humans -- depending on your point of view.
Entomology is the branch of science concerned with the study of insects and related organisms.
It involves studies of their biology, structure, identification, economic significance, and population management.
If basic science and discovery are to your liking, insects are fascinating and very appropriate model organisms for studying molecular biology, physiological processes, ecosystem functions, community ecology, and evolution.
If you are interested in applied ecology, managing insects is a full-time job for countless entomologists working in agriculture, disease epidemiology, forestry, and even the military.