- Box tree moth: when to check?
- Detect box tree moth infestation
- Box tree moth: What to do in the event of an infestation?
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Before it's too late, you should better recognize the box tree moth by its clear signs and then fight it in a targeted manner. We provide the necessary information.
You have probably already heard that the box tree moth (Cydalima perspectalis) is a dangerous pest on box trees (Buxus). But recognizing the pest and distinguishing it from other boxwood diseases is certainly not easy for everyone. We provide the information you need to protect your beloved box trees in time.
In order to recognize an infestation with the box tree moth early, it is essential to know how to control it properly. In this article you will learn when to check and how to recognize the infestation. Below are some combat tips.
Box tree moth: when to check?
Box tree moth eggs, caterpillars and moths are not found at all times of the year. The overwintered caterpillars are followed in spring by pupae and moths, then eggs and a new generation with the successive developmental stages. And these stages, unfortunately, occur at slightly different times each year depending on temperature and weather. The table below summarizes the appearance of eggs, caterpillars, pupae and cocoons. However, the normal case is shown here: Particularly warm years lead to a faster development of the moth, sometimes even a complete further generation can occur.
| month | April | May | June | July | August | September |
|---|---|---|---|---|---|---|
| Development State | Caterpillars (overwintered) | Cocoons | Moths, Eggs | Eggs, Caterpillars | Cocoons, moths | Moths, Eggs, Caterpillars |
| Recommendation | Use Traps | Use Traps | Use Traps | |||
| Generation | Generation previous year | Generation previous year | Generation 1 | Generation 1 | Generation 2 | Generation 2 |
Because thatThe actual occurrence of the pest in reality can differ from this representation, you must carry out your own checks.
Control box trees
From April the inside of boxwoods will be checked for overwintered borer caterpillars. You should carry out these checks of the interior and exterior of the shrubs - to be on the safe side - at least monthly until September. Around June, the overwintered generation has developed into moth moths, so that moths can also come to you from neighboring gardens or from much further away. Now you should start detecting their presence using pheromone traps. The Plantura borer trap, for example, is ideal for this. Recognizing the moth flight gives you information about when eggs and young caterpillars will be found on your box trees. This is the case about two weeks after the flight of the moth.
Detect box tree moth infestation
The box tree moth behaves quite secretively in almost all phases of life. Groups of up to 20 eggs are laid in the outer areas of the shrub as "egg mirrors" on the undersides of the leaves. They can only be spotted with good eyes in the period directly after the flight of the moth. As soon as the small, green-yellow larvae have hatched, they make their way inside the box tree, where they lodge between the caterpillar web and leaves and scrape the leaves with their mouthparts. In this phase, white webs are hidden inside the bush. When opened, they contain young larvae and crumbs of feces.
Older larvae move to the outside of the boxwood. In this phase, the infestation is easily recognizable: the caterpillars now eat whole leaves and the bark is also consumed - as a result, whole parts of the box tree die off and turn yellow. The fact that this damage was caused by the bush tree moth can be seen from the maximum 5 cm long, green-yellow caterpillars with black and white stripes and the characteristic black head capsule. The white webs now also appear more obviously. For metamorphosis, the caterpillars pupate into similarly colored, 2 cm long pupae, which are also spun into leaves. It is difficult to observe the flight of the moths without the use of pheromone traps, since the small butterflies are nocturnal.If there is a fragrant buddleia in the area (Buddleja davidii or Buddleja alternifolia), the box tree moth can sometimes be found there during the day. If you have discovered moths in your garden, you should keep a close eye out for eggs and larvae in the coming days to prevent a heavy infestation by fighting the moth.
Summary to detect box tree moth infestation:
- Eggs can be found shortly after the flight of the moth in the outer areas on the underside of leaves
- Young, yellowish larvae can be found inside the boxwood, hidden in white webs
- Older, darker colored larvae stay outside, shoots can die off and turn yellow, whole leaves are eaten, cocoons can be seen openly
- Puppets are in a web of caterpillar silk and leaves
- Moths can be discovered by box tree moth traps such as the Plantura moth trap or observed on butterfly bushes (Buddleja)
Box tree moth: What to do in the event of an infestation?
After discovering the infestation with box tree moths, don't hesitate and fight the infestation:
- Prune your boxwood about two weeks after you've seen the moths in flight. This will remove eggs and newly hatched larvae.
- Cut the webs with young caterpillars from inside the boxwood.
- If the caterpillars reach the outside area, you can use biological sprays like our Plantura Zünslerfrei XenTari®. In the preceding stages, the caterpillars are too well protected for this by their webs. If the infestation is low, you can collect the caterpillars by hand or wash them away with a hard jet of water. Here you can get information on the topic “Are box tree moths poisonous?” and you can read what you should consider when dealing with the box tree moth.
- Young larvae and eggs can be discarded alive, but older caterpillars or pupae should be killed before discarding them. Read everything else about the correct disposal of the box tree moth in this special article.
You can find detailed information on combating the box tree moth in our special article.