Recognize and fight (tree of life)

Leaf miner causes lasting harm to thuja

There are two leaf miners that infest the tree of life: the thuja leaf miner (Argyresthia thuiella) and the 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 miner moth has white-gray speckled wings and flies from May to June, the thuja miner moth is brown-winged and occurs from June to July.

Detect infestation by thuja leaf miner

Any discoloration of the thuja shoot tips should get your attention. Will be the tips Brown, examine them carefully. The following signs indicate an infestation by leaf miners:

• translucent or brown tips
• Tips are hollow inside
• black feces
• There are small caterpillars in the corridors

First measures to control the pest

If your thuja is attacked by leaf miners, you must act immediately, especially if an entire hedge is affected. Cut off all infected shoots and dispose of them in household waste - not in the

compost! You can burn them too.

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

The use of sprays is only required in the event of a very strong occurrence. 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 of combating leaf miners. Even means that are not classified as dangerous for bees must be used sparingly, as they pollute the environment.

An ecological control is possible with nettle manure. For this you have to put one 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 unpleasant smell for the neighbors.