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Box Tree Caterpillar Killer Nematodes

Number of Applications

What Are Box Tree Caterpillars?

Box Tree Caterpillars have rapidly become a serious pest of Box plants and Box hedges all across the UK. The Box Tree Caterpillars can develop in large numbers and in severe cases are capable of completely killing Box plants. The caterpillars willdefoliate the plants and damage the leaves, leaving them in a skeletal state. The caterpillars may evenbore into the bark of more mature Box plants if left untreated.

Identifying Box Tree Caterpillars

The Box Tree Moths will lay flat, pale yellow eggs that overlap each other in a flat sheet on the underside of the leaves on your Box plants. The larvae that hatch are of a greenish-yellow composition with black heads. As the larvae mature their green body develops dark brown stripes. Very mature larvae have thick black and thin white stripes down the body, with large black dots outlined in white. Look for clear webbing left on the plants which is created when the caterpillars achieve high numbers.

What Are Box Tree Killer Nematodes & How Can They Help?

Box Tree Caterpillar Killer contains Steinernema carpocapsae nematodes for the effective biological control of Box Tree Caterpillars. The nematodes enter the caterpillars via a natural opening, like the mouth, and feed on the contents of the pest. A natural bacterium is produced by the nematodes inside the caterpillars which kills the pest. Infected caterpillars will be completely broken down by the nematodes. The nematodes also reproduce inside the caterpillar, releasing more nematodes into the surrounding area.

How Do I Treat My Box Tree Caterpillar Infestation? 

1. Firstly, use our Box Tree Caterpillar Moth Traps:

The first step in protecting your plants is to set up one of our Box Tree Caterpillar Moth Traps. This will assist you in catching, monitoring and killing male Box Tree Moths. Once these are observed, it is likely that the Box tree Caterpillars will follow a few weeks later. By pre-empting their activity, and reducing moth numbers, you will have a greater chance of limiting an infestation. Moth mating and egg laying will also be reduced as a result.

2. Next, apply our Box Tree Caterpillar Killer Nematodes:

Nematodes can be used as an effective form of biological control against the caterpillars. The most successful species of nematode for Box Tree Caterpillar control is the Steinernema carpocapsae, which is contained within our Box Tree Caterpillar Killer Nematode pack. Apply these nematodes as soon as small caterpillars are observed.

3. Finally, use our Soil Boost Granules to help your Box plants recover

Box plants can be aided in their recovery from Box Tree Moth attack with the application of our Soil Boost Granules. Soil Boost acts as an organic slow release fertiliser, helping the Box plants achieve newly invigorated growth after stress and damage.

What Conditions Do The Nematodes Require?

Choose a humid or wet day to apply your Box Tree Caterpillar Killer Nematodes. Nematodes are UV-sensitive and will not survive long when exposed to bright, sunny conditions. Apply the nematodes early in the morning or early in the evening in order to utilise the optimum humidity levels.

When Should I Apply The Nematodes?

There are several generations of Box tree Caterpillars in a season. They are active from April - October, so the nematodes should be applied during this period.

How Do I Apply The Nematodes?

1. First open and empty the contents of your 25 million sachet of nematodes into a bucket or container of 2.5 litres of water and mix thoroughly.

2. Next, fill your sprayer (hand held sprayers should suffice, with filters removed - or use our Nema Super Sprayer for optimum nematode application) with the mixed 2.5 litres of nematode concentrate and add another 5.5 litres of water so you are left with 8 litres of nematode solution.

3. Finally, spray the Box plants, from top to bottom, ensuring the middle of the plant is also sprayed. Apply plenty of the spray solution to the foliage and where possible directly onto the caterpillars themselves. 

It is recommended that a second application is applied 7 days after your first application. This is to ensure the nematodes can get to the caterpillars not hit during the first application, and indeed any new small caterpillars that have since hatched from fresh egg laying.

Full instructions are applied on delivery.

How Many Nematodes Do I Need?

Box Tree Moth Caterpillar contains two sachets of 25 million nematodes, each 25 million pack will treat up to 35m2.

At least 250-500ml of nematode solution should be applied per square metre. 

Can I Store Nematodes?

You can store unopened nematode packs in a fridge but it is best to ensure you apply your nematodes as soon as possible for the best results.

Box Tree Killer nematodes are harmless to humans, pets and wildlife, and safe to apply to edible plants.

Customer Reviews

Based on 4 reviews Write a review

Customer Reviews

Based on 20 reviews
Diana Smith
Healthy box hedges

Two treatments with nematodes has completely cleared my box hedges of caterpillars. I will use the pheromone traps next spring and will hopefully stay on top of the problem.

Colin Howard
Totally successful and amazing

After the second application it was clear that the caterpillars were beginning to suffer and fairly soon could see shrivelled black ones. A couple of weeks on and having trimmed all the box now I can't see any new infestation but will continue with the nematodes in conjunction with the pheromone traps. This will just have to be a regular part of box maintenance from now on.

Paul Shepherd
Very stubborn.

Can box caterpillar be totally irradiated from my Buxus?After years of fighting this enemy I think not. While the nematodes do have an effect, it's only about 60-70%. However, it has been a phenomenal year for them, more than any of the last 5. They are here to stay and our Box plants are now endangered.

David H
May be working

Two applications, one week apart as advised, and no new caterpillars have appeared in the 11 days since the first application. I'll wait to see, but it would be good to be able to use a less noxious product than Resolva spray!
Only 4 stars because of two issues:
- No advice in instructions as to whether or not the nematodes might be washed off in the first rainfall ( in my case, just a few hours after application).
- One sachet produces a hugely greater volume of fluid (8 litres!) for spraying than the the average spray bottle will take and far more than may be needed per application (I have 5 box bushes and 1.5 litres was fine to cover). Needs smaller sachets, or instructions for using smaller amounts from sachets supplied. I created my own instructions and weighed out approx 3 g per 1.5 litre application from the 16 g of powder in the sachet.


It seems to have worked and my box plants are looking a lot healthier