Fight the leaf miner, leaf miner fly properly

The variety of leaf miners and leaf miners is almost unmanageable. The leaf miners can come up with a total of 3000 species. Over 900 of them are active in Europe.
There are 1000 species of leaf miner worldwide, of which well over 200 are up to mischief in Europe.

Each species specializes in a type of plant or certain leaf shapes.

How can the pests be recognized?

What they all have in common, however, is to eat away at the leaves from the inside out. The respective top and bottom pages remain unaffected. Instead, the larvae eat their way from cell to cell between these layers, leaving behind typical yellowish and brown spots. These can spread out evenly and almost round or run in lines and spirals.
The feeding marks dry up and are usually found in the middle of the leaves. More rarely, the hollowed-out tunnels are positioned at the edges of the foliage.

Leaf miners and leaf miners appear early in the year and also tolerate frost extremely well. They only take a short break in winter. Therefore, neither the tender, young canopy in spring nor the stronger one in autumn is safe from them.

The adult pests can also be recognized by their appearance:

• Leaf miners have transparent wings
• The bodies are slender, completely black, brown or marked with yellow spots
• Leaf miners are slim and show an elevated upper body when at rest
• The wings are brown or beige and white mostly black spots

Due to the numerous species and subspecies, the appearance can differ greatly. Because of this, it is not always easy to clearly identify the leaf miners and leaf miners. In addition, the adult insects are rarely found, while the larvae are hidden inside the leaf.

First measures in the event of an infestation

If an infestation is suspected, a few other measures should be taken in addition to hanging traps.

Since the larvae are found in the foliage of a wide variety of plants – from tomatoes to oak – it is first necessary to remove the affected leaves. In addition, it is important to examine every leaf for discoloration and signs of eating, if possible. If the larvae have pupated a few times, they display quite a large appetite. The leaves must therefore be checked every three to four days. As well as removing affected parts of the plant.
Incidentally, this does not only apply to the leaves that are still on the tree, bush or shrub. Even those that are already on the ground must be collected.

The next step is to destroy the damaging larvae. Since these are located in the foliage, the foliage must not end up in the compost or freely in the household waste. It should be hermetically sealed in plastic bags and only then disposed of in the garbage.
Another possibility is to dispose of the collected leaves in composting facilities. Here, however, a reference to a pest infestation should be made so that the leaves are burned or specially treated.

Preventive protection

Another inexpensive and simple measure is to cover the plant. However, this should only be done when all the affected leaves have been collected. Or before an infestation even takes place.

Garden fleece or a very close-meshed net can be used for covering, through the openings of which the adult moths and flies cannot pass.
In addition, the plant under the net should be equipped with the pheromone traps already mentioned. A weekly check prevents the leaf miners and leaf miners from spreading undetected underneath.

Use beneficial insects

In order to increase the success of the cover even further, beneficial insects should be used underneath.
Certain species of wasps have proven to be particularly successful in controlling leaf miners and leaf miners. Including:

• Parasitic wasps
• erzwespen
• Brackish wasps

These are freely available in stores and are simply left exposed on the affected plant or under the cover. As a result, the wasps lay their own eggs directly in the larvae. These eat their way through the pests and then slip out of them. If they no longer find enough larvae to feed and brood, they either move on or die. A plague of the wasps is therefore not to be expected.

But: Anyone who suffers from an allergy to wasp stings should carefully consider their use. Or take appropriate precautionary measures. Leaving it free in a tightly fitting cover is already a sensible step. In the event of repeated use, protective clothing should also be worn.

A clean garden

Leaves lying around, still partly green, have an attractive effect on leaf miners and leaf miners. Therefore, fallen leaves should be removed immediately.

If these already show noticeable discolouration, they again do not belong on the compost.
Welcome beneficial insects

In the wild, leaf miners and leaf miners are usually infested with numerous parasites. These prevent the pests from spreading uncontrollably and reduce the number to an inconspicuous level.

This does not necessarily mean that the garden will be free from the pests, but normally they will not be noticed at all.

For this reason, it is important to also welcome insects into the garden and not to pull out the spray bottle for every fly and beetle.

It is best to only use natural remedies, if at all, and only when there is a plague. Otherwise natural enemies will be destroyed again and again and their prey can spread unhindered. That in turn leads to the next plague. So if you ever plan to do an all-round deal with chemicals, you are not doing yourself, the garden or the environment a favor. And chemical insecticides tend to be nightly rather than beneficial for another reason.

Beware of insecticides

Insecticides are not only a danger to humans and animals. They are also partially responsible for the pests of leaf miners and flies that occur.

At least the broadband means. Because these do not ensure that the moths, flies and their larvae die. Instead, they provoke the development of resistance. The pests become immune to the agents and can no longer be deterred by them.

Therefore, such agents should really only be used if the measures already mentioned are ineffective. In addition, it is important not to use broad-spectrum products, but only insecticides that are specially tailored to the respective species.

The first clue for this is, as already mentioned, the infected plant species. The second is based on the shape of the feeding marks. Still not sure? An infected leaf should then be taken to a tree nursery, a nursery or a garden center – naturally packaged so that the larva cannot escape. A good, sharp photo can serve the purpose as well.
On the basis of this information, it is easier to identify the right species and then to combat it with precisely coordinated means.

Natural remedies against the winged pests

On the part of natural control, there are three different agents or active ingredients.

• Pyrethrum
• Natural fatty acids
• Nettle liquid manure

Pyrethrum is an extract from chrysanthemums. This active ingredient has a deterrent effect on insects and can thus prevent infestation with leaf miners and leaf miners as well as save an already infested plant. It can be used as an insecticide stick, whereby the substance gets through the substrate into the roots and finally into the leaves.

Additionally or alternatively, it can be sprayed directly onto the plant and thus work from the outside.

It is similar with products that contain natural fatty acids. These can also be used as sprays or sticks and then work either from the inside or the outside.
In any case, internal treatment is recommended. This works faster and more directly due to the position of the larvae of the moth and fly.

The last resort in the league is nettle liquid manure. To do this, pieces of nettle are placed in a bucket or barrel of water and left there for at least a week. The effect can be intensified if the plant parts are finely cut. The solution produced in this way is used to water the affected plants. On the one hand, this serves as an organic fertilizer and, on the other hand, it drives away pests.

If the infestation is already well advanced and many leaves have been removed, the liquid manure can also be used to spray the plants. That keeps new files off.

The best choice? – a combination

Each measure taken individually can already show success and reduce the number of leaf miners and leaf miners considerably.

However, just when the pests have reached the peak of their activity in summer, treatment alone is not enough. If the plant is to be saved, all measures must therefore be combined with one another. This is the only way to effectively prevent a new infestation and effectively remove the currently existing pests.

Conclusion
Leaf miners and leaf miners are not uncommon. Hence, they are almost inevitably present in every garden. But where little or no insecticides are used, there are enough natural enemies. So if you only discover a spotted leaf every now and then, all you have to do is remove and destroy the affected areas. No further treatment is then necessary. Only when the damage gets out of hand, i.e. a large part of the leaves is affected, do the above-mentioned measures become necessary.