The box tree moth is a butterfly that probably came to Central Europe around 2007 with plant imports from Asia. The moth lays its eggs on the leaves of the boxwood, where the caterpillars that finally hatch cause serious damage - often to the point of dying off the affected plants. In order to save the Buchs, quick action is often necessary.
The caterpillars of the box tree moth do great damage
Recognize
Unfortunately, an infestation is often only recognized when it is almost too late: the green colored caterpillars are well camouflaged and difficult to spot on the green leaves of the boxwood. In addition, with the slightest shock, they quickly retreat into the interior of the crown, where they are difficult to find. In order to recognize an infestation at an early stage, it makes sense to put up yellow boards in the vicinity of the box plantations from spring, especially in the surrounding trees. The moths caught there provide information on whether there is actually an infestation with the box tree moth or not. Typical signs of an actual infestation are, for example:
- white webs between the leaves and shoots
- Fecal crumbs on the leaves and shoots
- Eating marks on leaves and shoots
- initially yellow to brown spots
- later only skeletons remain
Box tree moths grow up to five centimeters long and are yellow to dark green in colour.
Treat
The most effective remedy against the box tree moth is to regularly collect the caterpillars. Since these often live deep in the crown and are difficult to get out of there, you can practically blow or flush them out with a leaf blower or a high-pressure device. For this purpose, you should cover the bottom area of the infested plants with foil to be able to collect the caterpillars that have fallen out more easily. The pests can also be sucked off with a vacuum cleaner. This works best if you use a crevice tool. Other effective measures against spread are:
- Prune infested box trees vigorously
- Pack clippings in airtight bags and dispose of with household waste
- never compost or put in the brown or green bin!
- Neem-based supplements kill many caterpillars
- Dilute concentrates and spray affected bushes with high-pressure equipment
- Repeat treatment several times at intervals of one week
- In the event of a severe infestation, use chemical preparations from specialist retailers
Make the garden bird-friendly too: While the caterpillars have not had any natural predators up until now, sparrows in particular seem to have discovered them as a welcome source of food.
Prevent
To prevent an infestation, you should cover the box trees with close-meshed nets from the beginning of March to make it more difficult for the butterflies to lay their eggs. These only live for a few days, so that the loss of the first generation means that only a few offspring are produced. You can also dust the endangered plants with algae lime, which the animals don't seem to like either.
tips
The caterpillars overwinter in fine webs inside the boxwood. A vigorous pruning in early spring as well as a thorough, preventative flushing with a neem preparation can prevent the worst.