The commonest tree by far in Barcelona is the London plane (Platanus x acerifolia), a hybrid of Turkish and American ancestors. It is tolerant of atmospheric pollution which it deals with by constantly shedding its flaky bark – itself a way its wild relatives combat parasites. Peel off their bark and you may find tiny Sycamore lace bugs (Corythucha ciliata), gorgeously intricate under the magnifying glass, although these pests suck on the tree’s sap and lead to its early death.

“Corythucha.ciliata.1” by I, Sarefo. Licensed under CC BY-SA 3.0 via Wikimedia Commons