Thuja turns brown - miner moth is guilty

The Content Of The Article:

If the tips of the thuja suddenly brown, it is usually one of the blame: the miner moth. Who does not intervene here and do something the same thing, must fear for his Thujen.

Guilt is the miner moth

Anyone who lets their gaze wander through the neighboring gardens will surely notice one thing: Thujen can be found everywhere. And that's not surprising, because Thujen are perfect hedge plants. Strung together, they can grow into a stately hedge in just a few years. So they offer a fast and opaque screen, which is also easy to maintain and cheap. So it does not matter if a plant comes in.

It is bad, however, when suddenly all the trees of life, as the Thujen are called, get brown tips and look sickly. Then at the latest, it's time to take a closer look at the plants. If the tips turn brown over time, that is a clear indication that something is wrong.

Most are affected several Thujen

Too often, Thujen suddenly turns brown and dies in no time. This is particularly annoying, of course, within a hedge. And just there it does not stay with a plant, here often several are affected. Responsible for the dying of plants is usually a culprit: the Miniermotte. To be precise, this is the Thuja miner moth.

Damage symptoms:

The Thuja miner's moth is a small butterfly that belongs to the family of gypsy moths. And this is precisely this puts his eggs on the leaves shed in June / July. The caterpillars that hatch from it then eat their way through the shoot tips and hollow them out. The result: The infested scales branches of the Thujen turn yellow from the top initially and then brown to gray over time.

In the meantime, the caterpillars pupate, which overwinter in the shoots. The new moth generation will hatch in June / July. Just like the previous generation, they again lay eggs on the shingled shoots of the Thuja. The whole game starts all over again.

Control measures:

Rear section:

If you experience an attack with the leafminer, fast action is important to save your trees. In case of a slight infestation, it is advisable to cut the shoot tips in the spring and thus before hatching of the moths. So you can curb the spread of the pest.

In case of a strong infestation, on the other hand, you have to do far more. Here even a drastic pruning of shoots is necessary. But do not worry, your Thujen will then again drive out splendidly.


Do not dispose of the affected branches over the compost but over the household waste. You can also burn the clippings. This will prevent the pests from spreading.


In addition, it is advisable to spray an insecticide against the miner moths. This agent is then on the one hand prevent oviposition and on the other hand prevent the penetration of freshly hatched caterpillars in the shoots. Therefore, it is always advisable to inject twice. Once in early June to meet the moths and once when the caterpillars hatch. Recommended insecticides for controlling miner moths are e.g. COMPO Triathlon Universal Insect-Free AF ​​(e.g., available here) with the active ingredients from nature or Bayer pest-free Calypso Perfect AF (available here, for example), which is non-venomous.

If you prefer to rely on natural pesticides, you can spray your Thujen with stinging nettle regularly. Fill 1 kilogram of stinging nettles and 10 liters of water in a vat, seal and leave in the sun for 14 days. Stirring regularly is important. Then you can use the manure directly.

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