The prospect of insects having emotions has been considered impossible, until recently studies may just have proven otherwise.
Earth has around 8.7 million different animal species. Of the incredible diversity of animals, there are very few that can actually have feelings, some of these few animals are dogs, rodents, elephants, birds, cats, horses etc. The commonality between all the animals previously mentioned is in their medium to large size, and there is a reason for this; emotions are caused by the Limbic system, a part of the brain of interconnected system, and the smaller the brain the less space to contain system that process and manage ''unessential'' information. Therefore animals with extremely small brains generally don't have space to have emotions, hence the undisputed theory and belief that insects have no emotions.
Scott Waddell, professor of neurobiology at the University of Oxford first started working on emotions in fruit flies, and through research found out that fruit flies do pay attention to what their peers are doing, and are able to learn from them. Although this is far from proving insects feel emotions it is a start, and displays that insects have a basic level of cognitive function.
Waddell's first experiment consisted of finding out if the fruit flies were able to find food faster when they were hungry compared to when they were not particularly hungry, the results showed that indeed the flies were able to have the feeling of ''hungry'' and were further motivated to find food because of it. This discovery implied that insects had feelings, but what about emotions, like sadness, happiness, and faer?
Extensive research was done by Lars Chittka, who leads a research group that studies bee cognition at Queen Mary, University of London, and she stated that "Let's say you're a bee that ends up in a spider web, and a spider is swiftly coming towards your across the web, it's not impossible that the escape responses are all triggered without any kind of emotions. But on the other hand, I find it hard to believe that this would happen without some form of fear" Scientific proof that insects can feel ''human emotions'' does not currently exist, but the field seems to be split up. Many specialists believe that insects are capable of feeling emotions, and many say they aren't. Either way, before killing an insect keep in mind that perhaps they are capable of feeling emotions.