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Horse Chestnut Scale
Horse chestnut scale, apparent as circular white spots on trunks
or large branches (and sometimes mistaken for pigeon droppings), is
caused by the insect Pulvinaria regalis.
This insect pest is occasionally found disfiguring trees in
urban localities, roadside pavements or other hard surfaced areas
such as patios. This insect has little effect on the health or
vigour of plants, therefore it is not something that needs to be
This is fortunate, as many of its host plants are too large to
be sprayed. On smaller trees in gardens it is feasible to brush or
wipe the mature scales and their eggs from the stems in April to
May to stop the next generation developing but on larger plants the
scale has to be tolerated.