Leaf miners are the most dangerous pests that can infest a thuja. If a severe infestation of the hedge is not treated immediately, this can lead to the tree of life dying off completely. This is how you recognize and fight an infestation of the miner moth on your thuja.

If the thuja turns brown, this can be the result of leaf miner infestation

Miner moth causes lasting damage to the Thuja

There are two leaf miners that infest the tree of life: thuja leaf miner (Argyresthia thuiella) and juniper leaf miner (Argyresthia trifasciata). Both are closely related, but differ in that the moths fly and lay their eggs at different times.

The juniper leaf miner has white-grey speckled wings and flies from May to June, the thuja leaf miner has brown wings and occurs from June to July.

Detect Thuja leaf miner infestation

Any discoloration of the thuja shoot tips should draw your attention. If the tips turn brown, examine them closely. The following signs indicate an infestation by leaf miners:

  • translucent or brown tips
  • Tips are hollow inside
  • black spots of feces
  • there are small caterpillars in the aisles

First steps to combat the pest

If your thuja is infested with leaf miners, you must take action immediately, especially if an entire hedge is affected. Cut off all affected shoots and dispose of them in the household waste - not in the compost! You can also burn them.

In the case of a severe infestation, the pruning must be very vigorous, but must not be carried out into the old wood.

The use of sprays is only necessary in the case of a very strong occurrence. In order for the control to be successful, spray once in June or July to catch the moths directly. A second treatment is given when the caterpillars have hatched.

What remedies are there against leaf miners?

The trade has a number of means to combat leaf miners. Even agents that are not dangerous to bees must be used sparingly, as they pollute the environment.

An ecological control is possible with stinging nettle manure. To do this, you need to soak a kilo of fresh nettles (without flowers!) in a barrel with ten liters of water for at least two weeks. The brew can then be sprayed directly and undiluted.

However, you should not underestimate the odor nuisance for the neighbors.

tips

Thuja shoot death can also be triggered by a fungal infestation. The shoots also turn brown, but unlike a pest infestation, they are not hollowed out.

Category:

Trees