The box tree moth has been spreading rapidly in our country for a number of years. It causes enormous damage and, if left untreated, will lead to the death of the beech tree.
The boxwood is a fairly easy-care plant. However, it is susceptible to various diseases and pests. This also includes the box tree moth, which has been spreading in Europe since the early 2000s. The larvae of the small butterfly, which originally comes from East Asia, are very stubborn and damage the box tree so much that it would die if left untreated. It is therefore essential to take suitable measures to combat and ideally also to prevent.
Life Cycle Bus Tree Moth
Each female lays up to 150 pale yellow, lens-shaped eggs on the underside of the leaves, from which the larvae hatch after only 3 days at temperatures above seven degrees Celsius. At a temperature of around 15 degrees Celsius, they go through a total of seven stages of development over a period of around ten weeks before they pupate.
By the way: From an ambient temperature of 20 degrees Celsius, the development cycle of the larvae is reduced to three weeks.
After pupating, it takes about a week for the moths, which are 40 to 45 millimeters in size, to hatch. These have a maximum lifespan of 9 days. During this time, the males mate with the female moths. The females then lay their eggs and the cycle begins again.
In this way, the box tree moth can have about 2 - 3 generations per year. The larvae of the last generation of the year hibernate inside the boxwood in a cocoon of twisted leaves, which they glue with their cobwebs, and begin feeding again in the spring.
Detect Infestation
The larvae of the box tree moth can grow up to five centimeters long, depending on their stage of development. They are yellow to dark green with white and black stripes and black spots. The head is also black.
Due to their coloration, the larvae of the box tree moth, which feed mainly inside the bush, are difficult to spot with the naked eye. But there are other indications of an infestation with the greenCaterpillars Notes:
- Web with droppings on leaves and shoots
- brown, eaten leaves
- Oviposition on the underside of leaves
- Butterfly pupae on the underside of leaves
- box tree moths fluttering around
Fight box tree moths
If you have found any indication of an infestation, you should start fighting the box tree moth immediately. Because as already mentioned, this multiplies rapidly.
❶ Collect caterpillars
You can try to collect the caterpillars of the box tree moth. Be sure to wear gloves when doing this. Because box trees are poisonous and can trigger allergic reactions even if they come into contact with the skin. Alternatively, you can also try to remove the pests with a vacuum cleaner. You should use a fine nozzle for this.
Tip: In order to be able to recognize fallen animals better, it is advisable to place a light-colored cloth under the plant.
Never dispose of the caterpillars in the compost. It is better to dispose of them in the residual waste. Just make sure they can't crawl out again.
❷ Pruning
In the case of a massive infestation, a strong pruning can be useful, in which you remove the affected parts of the plant. Again, a light-colored cloth under the plant helps to better identify fallen caterpillars.
Sometimes it is also necessary to discard the entire plant. To prevent the pests from spreading further, you should not dispose of the plant or the clippings on the compost. In the best case, burn them or dispose of them with the residual waste. For the latter option, it is advisable to carefully pack the plant or plant parts in plastic bags.
❸ Hose down with high-pressure cleaner
An effective way to remove the caterpillars from the plant is to use a pressure washer. Because these cannot hold on and are simply flushed out of the plant. Before you start, you should lay out a light-colored tarpaulin around and underneath the plant and fasten it securely. You can then easily collect and dispose of the caterpillars. Note, however, that they are quite agile animals and will try to crawl back into their hiding places. So hurry to collect them and repeat the pressure washer treatment if necessary to catch all the animals.
❹ Bringing natural enemies into the garden
Because itAlthough the box tree moth is a neozoan - an animal not originally native to us - there were no natural enemies for a long time and the moth was able to spread unhindered. In the meantime, however, the tide has turned decisively and some birds can be found in nature that like to eat the caterpillars. These include, for example, sparrows, great tits, redstarts and chaffinches. So make sure that birds feel at home in your garden. For example, offer bird feeders and feeders to attract them.
Tip: Wasps and hornets also eat the pests. It's better to come to terms with them than drive them out of your yard.
Note, however, that you still need to take additional measures as this will not get rid of all the caterpillars.
❺ Cover with dark foil
You can also take advantage of the fact that the larvae of the box tree moth cannot tolerate high temperatures when controlling them. All you have to do is wrap the affected plant in a dark foil on a sunny day.
The caterpillars cannot survive this enormous heat. However, any existing eggs will not be damaged. You should therefore repeat the procedure after about two weeks to kill off the newly hatched larvae as well.
Tip: In strong sunlight you should leave the film on the plant for a maximum of two hours. Otherwise it could be damaged.
❻ Use of insecticides
There are various preparations on the market that you can use to combat the caterpillars. You have the choice between biological and chemical insecticides. The preparations are sprayed at high pressure directly into the interior of the plant and are also distributed on the surface. The caterpillars absorb the active ingredients while eating.
The active ingredients thiacloprid and acetamiprid have proven to be particularly effective. Here, insecticides with acetamiprid should be given preference over other chemical insecticides. They work systemically. This means that the insecticide is absorbed by the plant and only released when the caterpillars start to tamper with the leaves and stems. This means that these insecticides are less dangerous for beneficial insects than insecticides that remain on the plant surface and become toxic upon contact.
Who would rather do without chemistry. can resort to biological insecticides. On the one hand, these are products thatbacterium Bacillus thuringiensis and on the other hand products with neem oil. The products are distributed on the plant in the same way as the chemical products, but are less aggressive and must therefore be reapplied after about ten days for a better effect.
Please note that while insecticides are very effective, they can pollute the environment. For the sake of the environment, these should only be used if all other measures have not been successful.Tip: Make sure that it does not rain for up to three days after application, otherwise the preparations will be washed off.
Prevent box tree moths
It is best if your box tree is not attacked by the caterpillars of the box tree moth in the first place. Here are a few ways to reduce the risk of an infestation.
Pheromone Traps
It is best to place pheromone traps near box trees in spring. These contain scents that attract male box tree moths. Once trapped, they cannot escape.
Pharomone traps serve to contain the population because the moths caught can no longer mate. On the other hand, they are an indication of an incipient infestation, so that you can start treatment in good time.
Protect boxwood with net
The best way to protect your plants is if the box tree moth doesn't get to them in the first place. There are also special nets with tight meshes that the moths cannot get through. When using such a net, make sure that you do not give the moths an opportunity to get under the net.
The net is only really effective if you leave it on the plant until the temperature drops below seven degrees Celsius again - like from March to November.
Infestation control at purchase
If you buy a new box tree, you should examine it very carefully to see whether it is already infected. This is often how the pests get into your own garden.
Use of algae lime
Even if the effectiveness has not been scientifically proven, more and more hobby gardeners are using algae lime and shell lime to combat the pest. Apparently, the caterpillars don't like the pollinated foliage, so they leave the plant alone.
Tip: If you also want to try to keep the box tree moth away from your plants with algae lime, you should do this on a dry daydust completely with the powdered lime.
Look for alternatives to boxwood
In Germany, the box tree moth usually only attacks box trees. Consequently, you can prevent the pest by using alternative plants. Here are a few examples for you:
- Buxus barberry (Berberis buxifolia)
- Evergreen barberries (Berberis)
- Hedge myrtle (Lonicera nitida)
- Yew (Taxus baccata)
- Tree of Life (Thuja occidentalis)
- Dwarf boxwood-like rhododendron (Rhododendron micranthum ‚Bloombux‚ ®)
- Blue and yellow cypress (Chamaecyparis lawsoniana)
- Ivy as a hedge (Hederea helix)
- Portuguese laurel (Prunus angustifolia)