Jayden Cockrane, of Balclutha Primary School, asks :-

Do insects see colour?

David Jarriault, a neurobiologist at the University of Otago, responded.

Indeed, most insects do see colours. The Nobel Laureate Karl von Frisch discovered this at the beginning of the last century proposing honeybees a sugar reward if they could recognise a given colour.

What makes an eye capable of seeing colours is the number of different photoreceptors it contains. In their compound eye, most insects have three different types of photoreceptors each one sensitive to a specific wavelength of light which gives them a trichromatic vision (as humans have). A few insects deviate from this basic scheme: some have only one photoreceptor and therefore cannot see any colour, whereas others have up to six different photoreceptors as the domestic fly does. Human and insect colour visions differ mainly in the range of colours that can be discriminated. Insect eyes have one type of photoreceptors sensitive to green (based on how we humans see this colour), another sensitive to blue and a third sensitive to ultraviolet. Humans have photoreceptors sensitive to red, green and blue. Combining the inputs from these different photoreceptors allows the brain of the insect (or of the human) to create a coloured perception of its environment.

And what about all the nocturnal insects flying around the streetlights? The world is as equally colourful at night as during the day, the human eye is just not sensitive enough to detect it. Some nocturnal insects can do it such as the moths. They have evolved sufficiently sensitive eyes to differentiate colours, even in a dark night. Colour vision is especially important for insects feeding on flowers' nectar. Petals' colours, namely ultra-violet highlight the reproductive parts and nectar sources of the flowers. Therefore, looking at a flower from a bee eye could reveal a very different pattern.