Box tree moth treatment: natural methods

Box tree moth treatment: natural methods

Treating the box tree moth without poison: here is our guide to natural methods of control against this annoying pest.

Even though your boxwoods (Buxus) might be under attack by the ravenous box tree moths (Cydalima perspectalis), it does not mean all is lost. It is possible to get rid of the box tree moth without poison and harsh chemicals. In this article, natural ways of treatment are explained.

Natural control of box tree moths

In the following, we discuss control methods with neem products, household remedies, beneficial organisms and, finally, Bacillus thuringiensis. At the end of this article, you will find a summary as to why we do not recommend the use of insecticides, that are sometimes unnecessarily reached for.

Combating box tree moths with neem products

Plant protection products obtained from the seed oil of the tropical neem tree are approved for organic farming and can be used against box tree moths. The insecticidal active ingredient contained in neem products is called azadirachtin. Even products that have a high dose of neem and are very processed are often considered ‘organic’ and marketed as such. However, with a little research it is easy to discover that they are very similar to conventional pesticides. The same safety regulations, that are advised with pesticide use, should be applied when using neem products. In addition, many of these products are damaging for predatory mites, different wasps, ladybirds, green lacewings, hoverflies and also fish and all of the animals that feed on them. For all these reasons, products with a high neem content can be described as ‘natural’ only to a limited extent. The use of at home prepared neem oil brews, which are lower dosed, however, is more natural and environment friendly.

Summary of neem products against the box tree moth:

  • Neem products are considered ‘organic’, which can be misleading
  • Many store bought neem products are still harmful to non-target organisms (such as bees or other beneficial organisms) similarly to the pesticides
  • Homemade mixtures with a low dose of neem oil can work effectively without being dangerous to nature

Treating box tree moths with household remedies

There are rumours of various household remedies against the box tree moth. Some describe an astonishing success that can turn big manufacturers green with envy. Some tricks work quite well, while others waste your time. One possible yet simple way is to collect the caterpillars by hand, for example, and it is effective in light to medium infestations, even if it is a bit time-consuming. The use of hedge trimmers at the right time can also eliminate a large proportion of eggs and young larvae in one swoop. For both approaches regular control – partly with pheromone traps – is crucial. If the caterpillars are on the outside of the box tree, a mixture of oil, vinegar and water can be used to combat them effectively. Using a jet of water from a gardening hose is even easier than the previous household remedies. The water washes the box tree vigorously from the inside and outside and this will bring noticeable results even with a severe infestation.

A practical method to prevent any treatment is to use nets to hinder the egg deposition of the adult box tree moths on the shrub. If this chance has passed, the box tree moth plague can still be subdued with heat using a dark garbage bag on a sunny day. You will find all the important information on getting rid of the box tree moth with household remedies in this article. In case of a serious box tree moth outbreak and severe damage to the bush, however, we recommend the choice of an effective natural remedy to save your box trees.

Summary of household remedies against the box tree moth:

  • Not every household remedy promoted as effective against the box tree moth is that impressive.
  • However, many simple methods can be very effective.
  • Collecting the caterpillars, removing them by pruning the bush, washing them away with a gardening hose, using nets and garbage bags may prevent or minimize infestations.
  • A severe infestation should be treated with an appropriate natural agent to protect your plants.

Tip: Are box tree moths poisonous? The caterpillars of the box tree moth are poisonous to (almost) any living being who puts them in their mouth. This is solely due to the fact that the moths feed on the box tree, which is also poisonous (even to humans). In this way, the moths store some of the box tree toxins in their bodies. You can read more about the poisonousness of the box tree moth here. Although the box tree moth is toxic, it is still safe to touch the caterpillars (just make sure that you wash your hands thoroughly afterwards). Once you get over the initial icky feeling about touching the box caterpillars, you can find out how they can be disposed of safely here.

Combating box tree moths with beneficial animals

There is one species that is an old acquaintance of many gardeners, who swear by it as a treatment method, that can take care of the voracious caterpillars. Nematodes of the species Steinernema carpocapsae parasitize on the caterpillars and thus eliminate even the caterpillars eating in their protective webbing. However, one drawback of this method is that the application of nematodes requires special adhesive and swelling agents in order to be effective.

In addition, it seems that the native fauna is getting used to the invasive moth species. Wasps and some garden birds – titmice, sparrows, redstarts and starlings – have already been observed exterminating the box tree caterpillars and moths.

It is possible that the feathered helpers will adapt to the poisonous nature of the box tree moth. In time perhaps, some natural predators, that can help against the moth, might appear. In order to increase the likelihood of this happening it is important to promote the helpful birds and other beneficial animals in our gardens.

Summary of beneficial animals against the box tree moth:

  • Nematodes of the species Steinernema carpocapsae can parasitize the box caterpillars; however, this method is only successful with the correct application method
  • Promoting native insects (such as wasps) and birds can help to get the box tree moth problem under control in the long term; in case of an acute infestation, natural sprays are recommended

Treating box tree moths with XenTari

The bacterium Bacillus thuringiensis occurs in soil and plants. It has the characteristic of producing the so-called ‘Bt toxins’. If these bacteria are eaten by insects, the crystalline proteins of the toxin are activated in their intestines. In this way they can pass through the intestinal wall and enter the haemolymph – the ‘blood’ of insects. Within a few days the poisoned insects die. Before that, further damage is prevented by an immediate halt of the feeding. The specificity of different bacterial types varies: many forms of the Bt toxins are only harmful to individual species. In this way, only the targeted species of beetles, butterflies, Hymenoptera, Diptera or nematodes is affected. The toxins have no effect on humans, other vertebrates or plants and the substance is completely biodegradable.

Why not treat the box tree moth with poison?

Harsh conventional pesticides seem to many people who are battling insect pests in their gardens the only viable option including in the struggle against the box tree moth. It is inarguable that the application is often fast and the effect quick and satisfactory. However, the use of poisons also has a number of disadvantages, which is why we recommend the use of natural agents.

Apart from the precision with which you need to apply the poisons, many commercial products are unfortunately also harmful to various non-target organisms. The non-target organisms are not intended to be negatively impacted by the product, however, they often are. Useful ground beetles, ladybirds, green lacewings, predatory mites and parasitoid wasps as well as various pollinating insects such as bees are susceptible to these agents. Moreover, consumers are more likely to avoid the products that are risky to bees. Although various products do not negatively impact the bees, they can still pose a threat to other groups of insects, that are just as important. Many of these insects are not only part of the ecosystem, but are also predators that counteract pests in our gardens. In addition, the toxins from the poisons must never get into water, neither directly, nor through sewers, drains or canals. They are extremely harmful to even the smallest aquatic organisms, which form the vital basis of food chains. All these reasons are (hopefully) compelling enough to combat pests without chemicals and to rely on natural alternatives that are just as effective.

Summary: why avoid using poison against the box tree moth?

  • The use of chemical pesticides is fast and effective.
  • However, the harsh chemical of the pesticides are harmful to the environment as well as the user. Additionally, they can be expensive.
  • Damage to beneficial organisms leads to greater problems with other harmful animals, which were kept in check by those beneficial organisms.
  • A great alternative are natural sprays, which are in no way inferior to conventional products in terms of effectiveness, but are much more gentle to the garden and the environment.

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