To be completely honest, the first time I saw an aggregation of hoverflies in a cage, I felt a pang of revulsion. I was just not accustomed to seeing so many flies crowded together! Perhaps this initial aversion was the result of some innate wiring that evolved in the human brain. After all, most people tend to stay away from areas with large numbers of flies because such places are usually unsanitary.
However, I soon became quite fond of these hoverflies. Indeed, I have been experimenting on them for almost nine months and they have become some of my closest companions. I watch them emerge into the world from their pupal cases, fly around as adults for around 30 days and then finally die. I am present for each stage of their cycle of life. Furthermore, I experience the excitement of discovery whenever I find out something new about their brains and behavior! I felt especially excited to discover that I can indeed alter the innate behavior of hoverflies, a finding that is the opposite of several previous research studies. Hoverflies are born with an innate attraction to a basic flower template: a yellow 3D-printed flower shape along with a floral odor. However, if I continually expose hoverflies to quinine solution, a very bitter tasting liquid, every time they are placed on top of this innately attractive flower template, they eventually stop being attracted to the flower model. Moreover, they usually generalize this learning to other flower models so that flower-like objects of different odors, shapes and even colors also become unattractive!
