Grounds staff have advised that the sticky substance falling from the trees all around campus is honey dew. It is a sugar rich sticky liquid, secreted by aphids and some scale insects as they feed on a plant.
When the aphids’ mouth part penetrates the phloem, they automatically excrete the sugary liquid.
It is particularly bad this year because we have had a mild wet winter and there weren’t the significant frosts we usually endure in Canterbury. These frosts usually control the aphid population.
The substance should easily wash off your car, but we advise that you don’t lick the honey dew off the leaves!
Read more info here.