United Kingdom: A new study by a group of researchers from Aberystwyth University has solved the mystery of why flies are attracted to blue objects. Theories have previously suggested that flies may mistake blue for shaded areas or perceive blue traps as resembling animals. However, these theories lacked substantial evidence.
To investigate this phenomenon, the researchers employed artificial neural networks inspired by the visual processing that occurs in fly brains. The networks were trained to distinguish between animals and leaf backgrounds, as well as shaded and unshaded surfaces, using the responses of the five types of photoreceptors found in a fly’s eye. They were then tasked with classifying blue flytraps.
The findings, which have undergone peer review and were published in the Proceedings of the Royal Society B journal, cast doubt on the notion that blue objects represent shade to flies. The neural networks correctly identified shade based on brightness and did not misclassify blue objects as shade.
However, when identifying animals, the networks compared the responses of blue- and green-sensitive photoreceptors. Consequently, they frequently mistook the blue traps for animals. This led the researchers to conclude that blue objects, including traps, bear a resemblance to potential animal hosts from a fly’s perspective.
Dr. Roger Santer, one of the researchers involved in the study, emphasised the practical implications of understanding the mechanisms behind fly attraction to coloured traps. By improving the colour of these traps to better capture flies, disease control efforts can be enhanced. Biting flies, such as tsetse flies, play a role in spreading diseases among humans and animals. Notably, the research findings could aid in combating human African trypanosomiasis (sleeping sickness) and controlling the stable fly, a globally damaging pest to livestock.
Field experiments have further supported the team’s conclusions, as tsetse flies captured in blue traps were found to have likely been seeking hosts rather than recently feeding. This study opens up new avenues for developing more effective fly control strategies, with important implications for disease prevention and livestock management.