Gardening

Boxwood moth: effective treatments


The boxwood moth is a caterpillar that attacks boxwood leaves for food, causing extensive damage and even dieback to boxwood.

Originally from Asia, it is now present in Europe, and in France since 2008.

The corn borer, (Cydalima perspectalis) is part of the Lepidoptera and more precisely of the Crambidae family.

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Recognize the boxwood moth

At the larval stage it is difficult to recognize the boxwood moth. But then it becomes a green caterpillar very recognizable, before evolving into a nymph then a white and brown butterfly with golden iridescence.

The boxwood moth is harmless to humans.

Boxwood moth and green caterpillar:

The green caterpillar has a black head and dark green streaks. We also note the presence of black dots.

The green boxwood caterpillar, or boxwood moth, is not stinging. It therefore presents no danger to humans and can be handled without protection.

You will also notice the appearance of small webs, such as cobwebs, characteristic of the boxwood moth.

These caterpillars then become white and brown butterflies that fly close to the boxwoods after dark.

  • When you have identified the boxwood moth, do not hesitate to tell your neighbors who have boxwood trees because they are very likely to be infested quickly.
  • The earlier the problem is treated, the better the chances of eradication.

Treatment of the boxwood moth

The first thing to do when you see green caterpillars in your boxwood is to remove them manually.

By quickly destroying the caterpillars, you facilitate the treatment.

But this action is not sufficient and it is also necessary to treat against the caterpillar in a biological way.

Product against the boxwood moth:

Even though this treatment has to be repeated several times a year, it is currently the most effective and the least harmful to the environment.

  • Biological control is the most effective control method.
  • The product to be sprayed isBacillus thuringiensis.
  • Spray all of the boxwoods, ideally on and under the leaves as egg laying takes place under the leaves.
  • The operation must be repeated every month until winter.

Be careful, after the 1st treatment, you will notice an improvement and regrowth of the leaves, but that will not definitively solve the problem.

  • The life cycle of the boxwood moth leads to several egg-laying in the year.
  • If you do not repeat the treatment, the untreated eggs or larvae will give rise to new invasions of green caterpillars.

Chemical insecticides or anti-caterpillars:

They have no additional advantage compared to Bacillus thuringiensis, authorized in organic farming, which we mentioned above.

They also have the downside of destroying other species of insects and the ecosystem in your garden or patio.

The chemicals negatively impact bees and other insects essential to nature.

  • Treatment: overcoming caterpillars

Trichotop buxus, a real predator

This predator was identified by a French company, Biotop.

The trichotop buxusis a microscopic wasp which must imperatively be put in contact with the boxwood moth at the larval stage, from the stage of reproduction of the butterfly.

Effective in small spaces, this solution continues to evolve and could probably be released on large scales in the near future.

Tip about the boxwood moth

Renewing the treatment at the end of winter or at the beginning of spring of the following year makes it possible to overcome the larvae that have overwintered in your box trees.


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© Guntar Feldmann

Video: Boxwood Leafminer - ID and Control (October 2020).