Common box is a slow-growing, evergreen small tree or shrub. Mature trees can grow to a height of 12m. They have a compact habit, with smooth grey bark which fissures with age, and green, downy stems.
Common box is monoecious, so both male and female flowers are found on the same tree in April and May. It is pollinated by both wind and bees, with each female flower developing into a green capsule and then ripening to a brown, woody seed case.
It is native from southern England to northern Morocco, and the Mediterranean region to Turkey. It thrives on hillsides, in woodland or scrub. In the UK, the best known wild populations of box are found on Box Hill in Surrey, the North Downs, the Chilterns and the Cotswolds, where it can grow in large numbers. However, box also grows commonly in our area too – with plenty of box found in Grovely wood for instance.
Perhaps you are most likely to come across box, not in the wild, but planted in parks and gardens, where it is a popular hedge plant and is a favourite species to topiarise. However, some people don’t like to have the plant in their garden as it has a smell associated with it that many find offensive – often described as resembling tomcat urine!
Box was seen as a sombre plant and in some areas sprigs of box were given to mourners at funerals to throw onto the coffin.
Common box timber is yellow, finely textured and hard. It is used for wood engraving and to make violin pegs and musical instruments such as flutes and oboes. Because box wood is so dense and hard, it is also used for making pestles, rolling pins, tool handles and printing blocks. In recent times it has become one of the favoured woods to replace ivory, especially when making chess pieces.
Prior to 2011, the main threat to box was box blight – a fungal disease that causes bare patches and dieback, especially on clipped plants used for hedging and topiary. It can also be affected by box sucker – a sap-sucking louse that causes stunted spring growth.
But these problems all pale into insignificance when compared to the latest issue!
The box-tree moth – (Cydalima perspectalis), is native to East Asia and became established in Europe in 2007. Although the first adult moth arrived in Britain in 2007, followed by several moths caught to light traps in 2008, caterpillars were not found in private gardens until 2011 in the home counties. By the end of 2014 the moth had become established in parts of London and surrounding areas.
Between 2015 and 2016, over 800 records of the moth were received. This jumped to over 3000 in 2017 and since 2018 have remained at more than 5000 a year. The box tree moth is now considered to be a “common resident”, being widely distributed across England, particularly the south-east. It is also present in Wales, Scotland, Ireland and Northern Ireland.
The caterpillars feed on the leaves within the webbing they make over the foliage and can completely defoliate box plants in days. Newly hatched caterpillars are greenish-yellow colour, with black heads. Older caterpillars reach up to 4cm (1¼in) in length and have a greenish/yellow body with thick black and thin white stripes along the length of the body.
Controlling these caterpillars is not easy. Many recommend picking the caterpillars off the plant by hand, which is OK if you only have a small infestation. Otherwise, one probably has to resort to an insecticidal spray. I would choose one based on pyrethrum/pyrethrins, as although these products are lethal to many insect species, they are harmless to pets and us! (They are very toxic to aquatic species though – so do not use it close to water).
Of course, you might just replace your box with a different species!
Finally, should you decide to try carving some box wood and decide to make a fleet of miniature ships, then think again. Box wood is the heaviest of our native timbers and will not float in water. Maybe a submarine fleet then!
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