The Box-tree Moth (Cydalima perspectalis) is a native of south-east Asia and until recently was unknown in Europe.

In 2007 it was discovered in Germany, probably imported with produce from China, and from then on it has spread rapidly.

It is, without doubt, a very invasive species and, as its name implies, the hedging plant Box is the food plant for its caterpillars.

Box is widely used in gardens for hedging and has been for a long time so it is a well-established plant just about everywhere.

Isle of Wight County Press: Box Tree Moth.

The Box-tree Moth.

Simultaneous with the discovery in Germany it was also recorded in Kent either in imported hedging plants or perhaps as a migrant having flown across the Channel.

It very quickly became established right across the country and, as it has two or three generations a year, numbers soon increased.

It was first recorded in the Isle of Wight in 2013 in a moth trap at Bonchurch.

These traps use a bright light to attract moths that then end up in a part of the trap they find difficult to escape from.

The trapper then records and photographs the catch and once this is completed the moths are released back where they were caught.

There are a number of people interested in this across the Island and a report is produced annually by the Island Recorder who then sends it on to Butterfly Conservation.

The next record in the Isle of Wight wasn’t until 2016 when two were noted, by 2020 there were 123 and this year, 2021, multiples are coming to the traps.

It should be noted that there will be far more moths in the Island than are actually seen and recorded as so few people are looking but more and more gardeners are reporting damage to their box hedges and this will only increase.

The caterpillars stick a number of leaves together and then make a white silk web round them thus giving themselves a safe place to live.

These webs are very obvious and are usually the first sign of the moth to be seen but once they start to eat the box leaves it is probably too late for the plant and it will turn brown and die.

It would appear that very little can be done about this infestation but research is continuing.

The moth has a wing span of between 38-42mm and has two distinctive colour forms; the normal white winged form and the black (melanic) form which is tinged with blue and purple.

Both are easily recognisable. There is little effective control if your Box bushes are badly attacked so it seems likely that this moth is here to stay.

Many gardeners are having to use alternative evergreen bushes for hedging which are unaffected by either Box-tree Moth caterpillars or box blight.

Click here to read more about box blight in this week's gardening column