As is so often the case, the pests are not a whim of nature, but were brought in by humans: “They probably came to us on a container ship because tree nurseries were keen on cheap box trees from Asia,” explains the Naturschutzbund Deutschland e.V. the background to the spread in Europe climes. Because the box tree moth is actually native to Japan and China. It was first sighted on the southern Upper Rhine in 2007, since then the small butterfly has been spreading and now also lives in the Netherlands, Switzerland, Austria, France and Great Britain. However, it is not the moth that causes so much damage to the plants – it is the caterpillars.
In contrast to the caterpillars, the box tree moth is usually not found on box trees, but on the underside of the leaves of other plants. However, the females prefer box trees that are not yet infested to lay their eggs, so that from March until late summer (up to four) new box tree moth generations appear again and again. The caterpillars hatch after just three days: they can grow up to five centimeters long, are yellow-green to dark green and black in color, have black dots and white bristles. Due to their preference for older leaves, they begin their feeding sprees inside the plant – and work their way outwards. As a result, the incipient defoliation of the boxwood usually remains undetected. A watchful eye is therefore important to detect the infestation.
In order to find out whether the box tree moth caterpillars are attacking your plants, you should look out for the following indications of an infestation:
Two to four generations of box tree moth caterpillars can invade your garden each year, so stay on the alert from spring through late summer—even if you think you’ve got rid of all the pests in your box trees. Some of the most effective ways to combat caterpillars include the following tips:
Prune box trees If none of the tricks mentioned have worked and your box trees are in danger of dying, there is only one thing left to do: you have to cut back the plants so that they can sprout again. Then burn the clippings or enclose them in a rubbish bag so that the box tree moth cannot spread further. You must then avoid infesting your plants again, as they would not survive a second attack.
Last but not least, you can of course also take preventive measures so that the box tree moth – or more precisely its caterpillars – does not infest your plants. These include the following:
Sources: Nabu buchsbaumzuensler.net
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