but as i was biking under the trees this week, my tires got stuck to the street a bit. i remembered the car being parked under it would turn into an dirty old car, as if parked there for a long time, in a few days. so i decided to exactly find out if the sticky street and dirty cars came from insects in the trees or from the trees itself.
it seems that in particular, aphids are attracted by the rich supply of sap of the leaves. in turn, they are "farmed" by ants for the production of the sap which the ants collect for their own use. the result, a dripping of excess sap (honeydew) onto the lower branches and leaves, streets and cars. and as this honeydew is often covered with a black mould, a black sticky layer is the result. happily enough this sticky layer is only annoying to us while the trees do not appear to experience any serious damage from the insects.