Box tree moth traps: how do they work?


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Wherever box tree moths are prevalent, box tree moth traps are in high demand. Discover the benefits of pheromone traps and find out whether they are an effective way of combating these destructive pests.

Box tree moth and box tree moth caterpillar
The box tree moth can cause extensive damage [Photo: Tomasz Klejdysz/]

Anyone who owns a boxwood (Buxus) will come across the box tree moth (Cydalima perspectalis) sooner or later, whether it is through finding them in their own garden, learning about them in a DIY store advert or hearing horror stories from other boxwood owners. The bad news is, this hungry pest is rapidly spreading across the UK. But before you succumb to the adverts in DIY stores promising an effortlessly moth-free summer, there are some things you need to know about box tree moth traps.

Read on to find out how box moth pheromone traps work, how effective they are, and how useful they can be – even if they cannot be used to control a box tree moth infestation.

How do box tree moth traps work?

The first thing you should know about box tree moth traps is that they do not contain insecticides and are not meant for controlling box tree moths. Instead, they use specific pheromones that can only be perceived by male box tree moths. The scent of these pheromones leads the male moth to believe a female is nearby and ready to mate, causing him to set off in search of the source of the attractant. When the moth arrives at the trap emitting this irresistible scent, it follows the trail to either a sticky glue board or into a trap funnel with a water trap waiting underneath. In any case, the moth gets trapped and eventually meets his demise. It is in this way that the traps are a reliable way of detecting the presence of these pests.

Box tree moth resting on wood
Male moths go wild for the scents of females during their lifetime [Photo: SanderMeertinsPhotography/]

Tip for using box tree moth water traps: To make water traps more effective, add a drop of washing up liquid to the collecting container. This reduces the water’s surface tension, thereby causing the moths to sink much faster when they land on the water, ultimately improving the trap’s success.

Are box tree moth traps effective?

Since only the female box tree moths emit pheromones to attract the males, it is only possible to make traps that catch male moths. The degree to which the moths are attracted depends on both the positioning of the trap and the mixture of attractants used. Our Plantura Box Tree Moth Trap is a water trap that covers an area of up to 180m2. Our pheromone traps are extremely robust and are therefore reusable. On top of that, they do not contain any insecticides. They come with six pheromone dispensers, which you should replace every four to six weeks.

Box Tree Moth Trap
Box Tree Moth Trap
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  • Reusable pheromone trap for monitoring box tree moth activity
  • For the early detection of infestations - covers an area of up to 180m2
  • 100% insecticide-free - not harmful to humans or pets

By no means will the traps capture all of the male box tree moths, but this is not what box tree moth traps are designed to do. Rather than preventing fertilisation and thus stopping the females from laying eggs, box tree moth pheromone traps are meant solely for detecting the presence of these nocturnal insects at an early stage. This allows you to anticipate imminent egg-laying and caterpillar development.

Using moth traps for detecting moth cycles

Seeing as the moths are nocturnal and the caterpillars are hard to spot due to their colouring and their whereabouts in the boxwood, it is very useful to know when the moths start flying. This way, you will know when to start looking out for the caterpillars and can act fast upon discovering them. While the development of the caterpillars depends on the weather, it generally follows this timeline: The adult moths (i.e. those capable of mating) develop from caterpillars that have survived the winter around the beginning of June, then quickly mate and die again. In July, the laid eggs develop into the first large generation of caterpillars of the year, then pupate and emerge as moths in August. These moths mate and lay eggs, and the caterpillars that hatch from them overwinter again until the following April, at which point the cycle starts all over again.

Larvae of box tree moth on leaf
There are several feeding larval stages which all differ in size [Photo: Cosmin Manci/]

Note: The developmental stages of the box tree moth may vary slightly from year to year. Due to the temperatures in some regions, it is also possible for three generations to be born per year, which makes close observation all the more important.

Considering the biology of the box tree moth, it makes sense to apply sprays or some other form of control at least twice a year – specifically when the caterpillars are active on the boxwood and are actually susceptible to such products. However, up to four cycles per year are possible. We therefore advise using box tree moth traps to continually monitor pest populations from March to October.

Box tree moth traps: worth it?

The development stages of the moth may shift, but by using a trap, such as our Plantura Box Tree Moth Trap, you will always know exactly when to expect an infestation of these hungry caterpillars. However, it is important to note that it is impossible to control a box tree caterpillar infestation using traps. Box tree moth traps only indicate when it is time to combat the box tree moth. Of course, this is an important prerequisite for an effective and targeted control of these pests, as the caterpillars hatch about one to two weeks after the sighting of the moths. In order to prevent the box moths from completely defoliating your boxwoods, you will need to act as quickly as possible. Using a biological spray is your best bet for controlling these bothersome caterpillars.

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