For about 12 years, hobby gardeners, especially here in Germany, have been suffering from a veritable invasion of the box tree moth. The voracious moth destroys lovingly tended Buxus hedges and globe trees in no time. Detailed knowledge about him is therefore a must for amateur gardeners.

Box tree moths are a serious threat

Table of Contents

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  1. the essentials in brief
  2. Box tree moth infestation
  3. Box tree moth poisonous?
  4. Combat box tree moths
  5. Discard boxwood
  6. Vulnerable Areas
  7. damage picture
  8. predators
  9. Resistance to box tree moths

    10. the essentials in brief

    • Box tree moths are difficult to spot early
    • Signs of an infestation are webs and gnawed foliage
    • Affected plant parts should be disposed of as soon as possible - and definitely not in the compost
    • Box tree moths can be collected or fought directly with ecological means

    The problem of box tree moth infestation

    A box tree moth infestation is not only annoying, but quite critical. Because apart from the fact that carefully tended box hedges or spherical box trees are ugly eaten up and covered with webs, it is also not easy to fight the box tree moth. On the one hand, an infestation is usually only recognized when the crown has already been unsightly eaten away, on the other hand, several generations can develop within one season.

    Another problem is that when you buy new plants, you can reintroduce yourself to the annoying pest. The box tree moth has spread so strongly, especially through the plant trade.

    Is the box tree moth poisonous?

    When it comes to exotic plants and insects, one quickly wonders whether they could possibly be poisonous to humans, birds or other animals. This is only indirectly the case with the box tree moth. He himself is not poisonous at first - but he becomes so in the course of the box tree occupation. The plant contains some toxins, especially alkaloids, which the larvae store in their bodies when they eat. As a result, the predators mentioned above also ingest these toxins when they feast on the caterpillars. However, this does not seem to pose a serious threat to the songbirds.

    The box tree moth itself is not poisonous

    What to do against the box tree moth?

    If an infestation is already underway, it is important to take countermeasures as early as possible. If you're thorough with the first generation, you may be able to rest for the rest of the season.

    Basically, for the sake of nature and your own health, you should always first try to combat the box tree moth biologically.

    mechanical methods

    Especially when the infestation is not very advanced, it is advisable to counteract the nuisance mechanically first. The credo "Fight naturally" is thus best fulfilled.

    Mechanical methods are:

    • collect
    • hosing down
    • blow off

    If the number of larvae is manageable, you can collect the animals with tweezers, for example, which of course requires some skill.

    The somewhat coarser variant is the garden hose or low-pressure cleaner or a leaf blower. With it, you can rinse or blow the caterpillars out of the bush, catching them on a film previously spread under the plant.

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    Ecological means: box tree moth control without chemicals

    Effective chemical-free agents are:

    • Bacillus thuringiensis products
    • oil products
    • vinegar
    • Lime and rock powder

    Bacillus thuringiensis - Xentari

    The bacterium Bacillus thuringiensis is an effective means of biological control of the box tree moth - it colonizes the caterpillars parasitically and thus causes them to die off. Products with the bacillus are sold under the name Xentari, for example by the Neudorff company "Raupenfrei".

    neem

    Products based on neem oil are currently booming as gentle crop protection agents. They are also an effective help against box tree moth plagues. The active ingredient azadriachtin from the neem tree seeds is stored in the leaves of the boxwood and inhibits moulting and thus the development of the caterpillars. A particular advantage is that they immediately stop eating the foliage. Note that the neem oil treatment should not be done in high heat if possible. In hot weather phases, it is therefore best to spray after sunset.

    In order to distribute the active ingredient as thoroughly as possible on the box, it is advisable to use a concentrate. This is diluted with water (the ratio is given on the product container) and placed in a disperser. To lower the surface tension of the mixture, you can add a drop of washing-up liquid or some soft soap (€44.90). This will give you more thorough coverage and better success rates.

    Ballistol Oil

    Ballistol oil can also be used as an antidote to a box tree moth plague. The advantage here is that the product is available in spray cans. This makes it easier to use. The oil works primarily by impeding the gas exchange of the eggs and clogging the airways of the larvae.

    vinegar

    Vinegar is also one of the proven home remedies against the box tree moth. It makes the leaves of the book inedible for the pests. It is best if you combine the vinegar with other home remedies, i.e. with oil and some water. This adds the airway blocking effect and increases the overall effect.

    baking powder

    Baking powder has always found many other uses apart from cake batter. In addition to stains, it is also said to help against the box tree moth. To do this, a solution is mixed with water and sprayed onto the box using a disperser.

    lime

    Algae lime in powder form is normally used successfully against fungal diseases on box trees. But lime can also work against the box tree moth. The leaves covered with the lime powder are unattractive for the larvae to eat. You can also try finely crushed shell limestone.

    bedrock powder

    A similar effect can be achieved with bedrock powder. If the rock flour (€14.13) is deposited on the leaves of the boxwood, it will be more difficult for the moth to lay eggs.

    when to squirt

    A spray treatment with ecological control liquids should be applied as soon as you notice a population of box tree moths. It is always better if you completely eradicate the first generation of moths in the season and thus prevent a subsequent generation. To effectively eliminate a pest population, you should do three thorough sprayings over a period of about 3 weeks.

    Chemicals

    Of course, chemical agents are generally not recommended because of the generally damaging effects on the biological system of the garden and the environment. However, if none of the ecological means help and you see no other way out, you can also fall back on them.

    Calypso

    Bayer's "pest-free Calypso" product, for example, works effectively. Apart from its not exactly environmentally friendly character, the application can also harm you. Above all, skin contact can cause allergic reactions. Under no circumstances should the product come into contact with the eyes or be swallowed.

    licetan

    Under the trade name "Lizetan", the Protect Garden company sells a spray that is based on the synthetically manufactured neem oil tree active ingredient azadriachtin. For example, the product "Lizetan Schädlingsfrei" has proven to be very effective for the box tree moth. In principle, it has the same systemic effect as organic neem products, but is less gentle and can cause allergic reactions.

    Bi 58

    Bi 58 is not approved for outdoor use, only use on ornamental plants in greenhouses is permitted. Bi 58 is a ready-to-use spray that works with the active ingredients abamectin and pyrethrine. Abamectin has a damaging effect on the nervous system of pests, pyrethrine acts as a contact poison. The sprayed insects die off quickly, but the agent has a long-term damaging, toxic effect on aquatic organisms.

    Careo

    The insecticide "Pest-free Careo" from Celaflor is a chemical spray that can be used against the box tree moth. Its active ingredient is the stomach poison acetamiprid, which paralyzes and kills the pests. However, the concentrate is also toxic to aquatic organisms.

    pheromone traps

    Traps can also be used to combat box tree moth populations. Especially pheromone traps are used against the pest.
    A pheromone trap takes advantage of attraction to scent in the mating process of pest insects. Synthetically produced attractants of the female insects, technically known as pheromones, are either combined with glue on small tablets or injected into a trap container. With the first method, the attracted male insects simply stick, with the second they get into the trap container, which they can no longer leave. By catching the male boxwood butterflies, the mating rate and thus reproduction is reduced.

    Pheromone traps have a rather weak effect

    functionality

    The container traps usually consist of a trap body and two depot chambers for the attractant, a pheromone gel that is filled in using a syringe. This gel is usually also available as a refill pack. Traps from Natria (Bayer), from Solabiol or from Neudorff work with this principle. The Neudorff trap is available under the brand name Neudomon as a specific boxwood moth variant.

    Experiences: moderate effectiveness

    The trap method is fairly inexpensive, because the trap only has to be hung up and the attractant depots have to be refilled once every few weeks over the course of the season. However, the effect is not nearly as effective as with targeted treatments on the box with home remedies and spa treatments. In the end, the number of males is only slightly reduced, but by no means set to zero. As a rule, there are still individuals left who can mate with females.

    Pheromone traps are therefore actually more used in agriculture and forestry for monitoring, i.e. for diagnosing the extent of a population, and less for actual damage limitation. In this respect, you can also use such traps for inspection, i.e. to determine whether box tree moths are in your garden at all. In this way, you can prepare for targeted combat.

    tips

    So that you don't get into trouble with the box tree moth in the first place, it's worth taking precautions. It all starts with getting the plants. Inspect a boxwood tree with eagle eyes before you buy it: if you see fine webs or small crumbs of droppings, a boxwood moth infestation is fairly certain.

    Covering box trees with a fine mesh can also be helpful as it discourages the moths from laying eggs.

    Dispose of infested boxwood

    Finally, a word about the correct disposal of infested boxwood branches or whole plants. Since the pest has spread so massively in recent years, every hobby gardener has a certain responsibility to prevent further spread. Although there is no official obligation to report an infestation of box tree moths, in the interest of the general gardening community, the fight should be carried out as thoroughly as possible.

    Infested parts of the plant should never be composted

    Important is:

    • No disposal on the compost
    • Ideal: burn

    Infested plant material does not belong in the compost!

    So if you are dealing with a heavy, stubborn population and your box trees are badly eaten away, it is necessary to thoroughly remove infested plant material not only for aesthetic reasons but also to prevent further spread. Pupated borers can still sit on the eaten and dead shoots of a Buxus that come together during a radical pruning. So that they cannot cause any further damage, the clippings must not be disposed of in the compost. There, the caterpillars can develop further and the trouble begins again.

    Burning is best

    It is best to have trimmed, infested boxwood branches burned at a recycling facility. This is the safest way to get rid of the pest. At the very least, you should dispose of the clippings in the household waste, where any larvae that are still present have less of a chance of developing into moths.

    Particularly vulnerable areas

    In Germany, the areas in the Rhineland, in the Rhine-Main area and in the southwest are particularly badly affected by the box tree moth plague. The pest feels particularly comfortable here because of the warm climate. That is why the German Horticultural Association even explicitly warns against planting box trees in these regions.

    background

    Facts about the box tree moth

    Zoology, origin and distribution
    The box tree moth is zoologically called Glyphodes perspectalis and is a small butterfly. It belongs to the snout moth family, which is mainly found in tropical regions. The box tree moth is also not native to us. It originally comes from East Asia, from where it was introduced to us in Central Europe around 2007 - probably through the plant trade. Since then, to the chagrin of many hobby gardeners, its spread has spread rapidly. Unfortunately, he is also not easy to fight. However, you don't have to give up.

    In order to be able to recognize the box tree moth, you also need an attentive eye, because the caterpillars are difficult to spot in the green box leaves. However, the earlier an infestation is detected, the higher the chances of successful control.

    appearance of the butterflies
    An adult box tree moth has a broad, splayed triangular shape, about 40 mm wide and 25 mm long. Its wings are creamy white and bordered with brown. If you look closely, you can see a small crescent-shaped spot on both sides in the middle of the upper brown border. But there are also completely brown specimens.

    The butterflies of the box tree moth are rather inconspicuous

    appearance of the caterpillars
    The caterpillar of the box tree moth is about 5 cm long and yellowish green in colour. A black-brown and white dotted stripe pattern runs down the back. The head is black and the caterpillar has white bristles all over its body.

    Actual damage from larvae

    The actual culprits responsible for the destroyed box trees are not the adult moths, but the larvae. Once a box tree moth has grown into a finished butterfly, it almost only has the task of taking care of offspring and does not live long after that. The pest thus spends the main part of its existence preparing itself by eating for this purpose of laying its eggs. Incidentally, as a moth, it is less likely to be found on box trees, but rather on other plants.

    The box tree moth, on the other hand, always lays its eggs on box trees. There the larvae hatch and cover themselves in white webs throughout the winter. The caterpillars only become active when the frost has noticeably gone. Then they leave their web cave and begin to feast on the leaves of their host plant. This gives them energy to grow and to go through several stages of development.
    Finally, like all butterflies, they retreat into a chrysalis in order to transform into a moth.

    damage picture

    Webbed and eaten leaves are a sure sign of a box tree moth infestation

    Since the box tree moth caterpillars that have hatched spend the winter in relatively clearly visible webs in the box tree, you can already recognize an infestation in the cold season.

    When the caterpillars start their voracious activity in March, the plant will gradually be defoliated and, if no countermeasures are taken, will soon give a sadly naked picture. So keep an eye on your bushes from March at the latest - because the caterpillars start to eat from the inside of the crown, so that the sapling looks flawless from the outside for even longer.

    When there are no juicy leaves left, the caterpillars also attack the bark of the younger shoots and kill them. Incidentally, a clear indication of a box tree moth plague are the remaining leaf skeletons, because these are spurned by the parasites.

    predators

    It is true that the box tree moth only recently immigrated to us and its natural predators from China and Co. did not accompany it.Nevertheless, some adaptable native animal species seem to have adapted to the new food supply and put the box tree moth larvae on their menu. These include above all sparrows, chaffinches, great tits and some wasp species.

    Can a box tree be resistant to the box tree moth?

    In the course of the massive spread of the box tree moth, the demand for Buxus varieties that are resistant to the pest is naturally increasing. After all, the boxwood is part of the well-established cultural heritage of local horticultural history and is very popular.

    Sobering reality

    Unfortunately, there are still no resistant Buxus varieties. So if you absolutely do not want to do without the classic hedge and ball cut plants, you have to live with the risk of a borer infestation and, if the worst comes to the worst, accept the effort to combat it.

    Little bright spot

    But it is somewhat comforting that there are at least variants that seem to be a little less vulnerable. These include, above all, the varieties of the small-leaved boxwood, botanically Buxus microphylla. Attractive varieties include 'Herrenhausen' or 'Faulkner'.

    If you want to be on the safe side and don't get too attached to real Buxus trees, switching to similar small trees is also worth considering. In this way you can avoid the annoying borer in the long term and still enjoy pruning-tolerant, accurately formable and robust shrubs.

    Suggestions would be:

    • dwarf privet
    • dwarf yew
    • Small-leaved rhododendron

    dwarf privet

    The varieties of the dwarf privet in particular are an alternative to boxwood. With its small, elliptical leaves, it is very similar to boxwood and also develops a very comparable, low-dense habit. Compared to other privet species, it remains fairly small at 70 to 100 cm in height and also grows quite slowly. It is also undemanding, hardy and evergreen.

    dwarf yew

    The dwarf yew, for example, has a slightly more needle-like appearance, but is just as dark green and dense. Like boxwood, it can be cultivated in tubs to form clearly formed silhouettes and is just as evergreen. The small shrub is also suitable for edging beds. A nice addition is the red berry fruit decoration!

    Small-leaved rhododendron

    The small-leaved rhododendron has slightly larger leaves that are small for its genus. Like the dwarf yew, it grows compact and spherical on its own and is therefore a good substitute for boxwood. It is also very robust and evergreen and boasts decorative flowers.

Category:

Animals in the garden