The most common and lucrative opportunity is in agriculture. This involves working with pest species and how to control them. Another common job opportunity is in vector control – think of malaria mosquitoes.
Both of those can be done with both practical work and lab work. For example, on physiology or life cycles of the pests/disease vectors can lead to new ways to disrupt them. So it’s not just “go to a field, ID whatever’s there and spray insecticide”, although if you’re biochemistry-oriented, insecticide research is another avenue!.
Another practical field is in environmental monitoring. You can monitor the state of rivers or lakes or sewage plants by looking at the insects present, their abundance and their taxonomy. Ditto for forests, grasslands, and other habitats. This also involves some research on environmental tolerance of the species.
A mostly practical field is forensic entomology. You can tell how long ago a corpse died by looking at the insects and insect life stages are on/in it. Academic research is also possible here, but it’s mostly just practical fieldwork.
Those are the main practical fields, and where most entomologists end up. The rest is academic.
You can go into systematics and taxonomy, where you will get hired by a university or museum to do work describing new species, doing fieldwork to discover new species, or revising the taxonomy of what’s described already. Related to all of this is the phylogenetic aspect – reconstructing their evolutionary history.
Related to that is palaeoentomology, but you will need to make sure you take a couple of palaeontology and geology modules in your studies. It’s the same as the previous paragraph, except with fossils. Although keep in mind that nowadays, you often have to examine recent animals as well as fossils, so there’s not much difference.
You can also go into conservation, which involves research, fieldwork and some diplomacy and public education. Research and fieldwork are finding out life cycles and environmental tolerances of the species, habitats, distribution, population monitoring, etc. The diplomacy is to get politicians to listen to you, and public education is to teach laypeople so they vote for the politicians that will listen to you.
Note that these jobs aren’t mutually exclusive – you might discover a new species in your wheat field and get to describe it, and then do research on it to see its tolerances, then monitor its population to see if it needs conservation. Interdisciplinarity is all the rage these days, so try not to overspecialise.