Gardeners beware! Blight of box tree caterpillar hits Bucks

Experts warn gardeners as cases of the Asian box tree caterpillar, which strips popular topiary bushes bare, are reported in Bucks

Gardeners are being warned to watch out for an invasive and destructive pest which is threatening box trees, with cases reported in Bucks.

The Royal Horticultural Society has reported cases of Diaphania perspectalis, the Asian box tree caterpillar, which strips hedges it infects bare, have doubled.

Now infected plants have been spotted in Buckinghamshire and east London.

The RHS found eight cases in May in Stoke Poges, as well as Woodford and Loughton in east London.

The pest is relatively new in Britain arriving in Europe in 2005 in a consignment of box plants sent from China to Germany.

The pest is an inch-long caterpillar a greenish yellow colour with black stripes.

Five years ago cases were reported after larvae were spotted in a Surrey nursery.

There have been sporadic infestations ever since and the caterpillars are causing severe defoliation indicating the moth is likely to become a serious problem.

There were four cases in the whole of 2013 – the eight sightings are the equivalent of all sightings since 2011, which the RHS says is a sign of establishment.


Common name Box tree caterpillar

Scientific name Cydalima perspectalis

Plants affected Box (Buxus)

Main symptoms Foliage is eaten and covered in webbing

Most active April-October

Advice from the RHS

Gardeners are likely to become aware of box tree caterpillar when they find webbing and caterpillars on box plants.

The pale yellow flattish eggs are laid sheet-like, overlapping each other on the underside of box leaves

Newly hatched caterpillars are greenish-yellow, with black heads. Older caterpillars reach up to 4cm (1?in) in length and have a greenish/yellow body with thick black and thin white stripes along the length of the body

The pupae are concealed in a cocoon of white webbing spun among leaves and twigs

The adult moth usually has white wings with a faintly iridescent brown border, although the wings can be completely brown or clear. The moth has a wingspan of around 4cm (1?in)

The caterpillars eat box leaves and produce webbing over their feeding area. Plants may also show patches of dieback which may be especially apparent on trimmed plants. This is not to be confused with dieback caused by the disease known as box blight

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