How to get rid of the box tree moth?

How to get rid of the box tree moth?

The box tree moth is feared by many gardeners and box tree lovers. All the methods of eliminating the box tree moth are explained here.

The box tree moth (Cydalima perspectalis) is an insatiable pest. In a case of a heavy infestation a young or a small box tree (Buxus) can be completely defoliated in a matter of days. Although the robust bushes often survive the moth plague – their appearance suffers after the caterpillars’ feast. Unfortunately, repeated and prolonged infestation can even lead to the death of the plant. We will introduce you to the various methods which effectively combat the harmful box caterpillar and will inform you about the advantages and disadvantages.

Box tree moth treatment

At what time and with what chemical spray, household remedy or natural product can the box tree moth be eradicated? In the following, you will find a variety of methods as well as information on their effectiveness and references to our special comprehensive articles. This is an overview of the various control methods:

Means of treatmentReliableImmediate halt in feeding Gentle to beesGentle to beneficial animalsNaturalEasy to use/practical
Pheromone trapsNoNoYesYesYesYes
Conventional pesticidesYesYesYesNoNoNo
Neem productsYesYesYesNoYesNo
Homemade remediesLessNoYesYesYesDepends

Box tree moth treatment: when is the right time

When to use sprays against the box tree moth and how about the other measures of treatment? This depends on the stages of the development of the pest. Young box caterpillars are protected from the agents in sprays because they live in the webs inside the shrubs. The pupae in cocoons are also well sheltered. However, eggs and freshly hatched larvae can be removed from the bush by pruning, and the older caterpillars, that live on the outside of the box tree, can be treated with sprays or simply rinsed away with water from the gardening hose. In order to fully understand when and which measure has an effect, you must get to know your enemy: eggs, caterpillars and moths occur in a very specific order and in 2 to 3 generations a year. This article describes the biology of the box tree moth and explains when and what method to use.

Tip: The use of pheromone traps is an effective tool to follow the development of the box tree moth in your own garden. Pheromone traps allow you to act directly and can give you a heads up before the larvae hatch. The traps emit sexual pheromones, which attract the males of the box tree moth. Based on the activity of the moth, it can be established when exactly the eggs are laid and predicted when the caterpillars will occur.

Treating box tree moths chemically

If you want to control the box tree moth with insecticides, there are various products and active ingredients available, which are summarized in the table below. However, these insecticides can also have harmful effects, which is also indicated in the table under this paragraph. Please note that products that are marketed as ‘non-hazardous to bees’ often have an enormously harmful effect on other no less important or useful organisms. For this reason, we strongly advise against using any of the active ingredients listed below in your garden. If you would like to find out more about the properties of spray agents, you can do so in a list of authorities approved plant protection products.

Active ingredientEffectNotes
AzadirachtinContact poison, inhibits feeding, larval development and reproduction, causes deathHarmful to various insects, arachnids and aquatic organisms
ThiaclopridSystemic and contact poison, causes paralysis and deathIn undiluted form harmful to humans, harmful to various insects, arachnids and aquatic organisms
AcetamipridSystemic and contact poison, causes paralysis and deathSlightly harmful to various insects, arachnids and aquatic organisms
Pyrethrin, rapseed oilContact poison, anaesthesia and deathHarmful to various insects, arachnids and water organisms

Note: The active ingredient azadirachtin is obtained from the seeds of the neem tree. Neem products are frequently used in organic farming and are considered ‘organic’. However, the isolated active ingredient is equally harmful to many non-target organisms just as conventional insecticides. Homemade brews made from natural neem oil, on the other hand, are often less concentrated and also contain substances that have a deterring effect on all insects which can prevent contact with the harmful azadirachtin.

Treating box tree moths naturally

We recommend to combat the box tree moth naturally. The use of low doses of neem oil is a possible option. The spray liquid must be applied regularly and also acts as an effective deterrent due to the ingredients Salannin and Meliantriol. It simply keeps the moth at a distance because of the unpleasant smell. Next, the use of beneficial insects is also a possible solution: nematodes of the species Steinernema carpocapsae parasitize and kill the box caterpillars. However, in order for the nematodes to reach the caterpillars at all, a very special formula of the spray liquid is necessary, containing bonding and swelling agents. Promoting and supporting beneficial organisms is the best and most nature friendly option. Native garden birds and wasps feed on the moth and caterpillars and help inhibit the spread of the pest.

Authorities and experts recommend the use of highly specific Bt preparations. They contain a special strain of the bacterium Bacillus thuringiensis (Bt), which exclusively impact the harmful box tree moth caterpillars. The bacterium has to be absorbed by the caterpillar through feeding, a toxin is released in their intestine, which causes the insects to stop feeding and subsequently die. Caterpillars that do not feed on the box tree are not attacked by the bacterium – admirals, swallowtails and other moths and butterflies are therefore safe.

This article provides a comprehensive guide to the possibilities of natural control.

Treating box tree moth with household remedies

The box tree moth can be kept in check to a certain extent with some easy and homemade tips and tricks. If the infestation is small, it is still worth collecting the caterpillars by hand and cutting out the webs manually. If you observe the flight of the nocturnal moths – and thus the mating – by means of pheromone traps and use the hedge trimmer two weeks later at the latest, you can remove the eggs and freshly hatched larvae that have been laid on the outside of the bush. Covering the entire box tree using a net can curb the egg deposition right from the start. The nets of course obstruct the view of the beautiful shrub, though. If you want to reduce a heavy infestation quickly, you can also use the gardening hose and wash away the box caterpillars out of the buxus branches. Or you can cover up individual box trees in black plastic bags and let the sun heat up the shrub to eliminate the caterpillars.

cydalima perspectalis
The voracious caterpillars can be treated with household remedies [ Zerbor]

We would advise against the use of baking powder and algae lime, because these agents are ineffective or even harmful for your box tree. Last but not least, supporting birds and wasps in the garden is a great preventive measure against the box tree moth. These species feed on the moths (possibly even the box caterpillars) and thus reduce the pest population. You can find detailed information about these household remedies in this article. Please note that household remedies often require more time and effort and can be less successful than some specially developed remedies.

Tip: The caterpillars of the box tree moth contain many toxins, which they absorb from the equally poisonous boxwood. Just as it is possible for most people to touch the box tree, skin contact with the box tree moth is not dangerous. However, please do not eat either the moths and caterpillars or the box tree. Here you will find further information on the poisonousness of the box tree moth.

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