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Box moth second flush warning

AJB Temple

AJB Temple

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Usually box moth arrives in spring and there is a repeat season in summer. This year the first flush was early (see previous thread) and the second flush is here already. We have seen caterpillars today on our buxus in mid Kent and are spraying today. It's been wet and warm. If you have valuable buxus check them under the leaves carefully. We use pheromone traps but have caught no males in the past 10 days.
 
Out of interest have you ever tried trichogramma wasps against the moths? I tried a predatory wasp against whitefly some years back, with great success, but that was in a greenhouse. Wondered what results might be obtained outdoors
 
No Tris and for good reason. I follow the standard horticultural guidance in the UK and EU. These are moths, so typically active at night and the caterpillars are on the underside of leaves and there is some protection from white webbing. I am aware that the Asian Hornet is known to predate this family of moths, but Asian hornets are very bad news - and in fact a notifiable pest in the UK - as they predate honey bee hives badly. We have about 180,000 bees in our garden and as with most bee keepers we have Asian Hornet traps in place. Both species are unwelcome visitors to the EU and UK.
 
My chief caterpillar hunter did a thorough sweep earlier and did not find one. I shall still spray again next week. The pheromone traps have not yet trapped anything but I will still renew the pheromone later in the summer.
 
My understanding that they are an ichneumon wasp with adults around 1mm who target the moth eggs with their own eggs. Won't stop adults but should reduce if not eliminate the caterpillar stage.

Not sure how species selective they are as they are also sold to combat cabbage moth and clothes moth.


Have you caught any Asian hornets yet? The 'normal' ones are a regular problem here and we usually have 4 to 5 nests destroyed each year around the grounds. There are a lot of bumble bee species and a couple of wild colonies here so we try to keep hornets down
 
Nope - not caught any Asians myself, but they have been seen in Kent, Isle of Wight, Sussex, Hampshire etc this year. The bee community is very concerned at the spread. ordinary hornets are not an issue as the guard bees in a group can deal with them. They can't repel the large Asian yellow leg hornets though. I will look further into the wasps but it is not listed by RHS as being a solution nor is it on the German websites (BM prevalent there). Our main aim is to stop the issue before it begins by trapping the males and killing any hatched caterpillars. The eggs are at most 1mm and very hard to find. I keep in touch with a pro (National Trust) guy who generally advises the head gardeners in the big gardens in the south.
 
After a little digging it is a grey area, 2 species require a release licence from DEFRA, one doesn't. The one that doesn't requires a minimum 18 degrees centigrade and is mostly sold to combat indoor pest moth species. Two UK companies are selling it as an outdoor pest control so I might email them for clarification.

This all reminds me of the situation with bacillus thuringiensis some years back. Still available to professional users, supposedly banned for amateurs yet readily bought online
 
Hi Tris. Folloing on from your thoughts, I've looked at the wasp control method in a bit more detail and asked the head gardener at Sissinghurst (they have a lot of Box and it being a preservation aim they are motivated to keep it) about it via whats app. He said trials are taking place at Kew with card hanging systems for pest control but not aimed at Buxus. He is unaware of any parasitic system in the UK that has been trialled.

Looking at the suppliers of ichneumon wasps, they require one card per square metre indoors. And a 10 card supply is £90, where the cards are replaced at two week intervals (so 40 cards in all for £90). To cover a garden area, given loss of insects to weather and wind and natural dispersion, is likely to require a lot of cards to get sensible coverage. And it needs to cover March to late August. I can't see it being an economic or practical proposition compared with spraying.

German trials have shown some bird predation of the caterpillars.

It seems the first and best line of defence is pheremone traps which are fairly cheap and very effective at getting the majority of male moths as long as the traps are out early enough. This is the method used at Sissinghurst and Great Dixter for example. Dixter does not have much box.
 
I know the square root of zilch about any of this. But I have a short section of Box outside the front of the house and it is looking very sad:box.jpg

As you can see, there is a bit of new growth in the TR corner, but the rest looks dead. But when you look inside the foliage there is plenty of signs of life. Is this normal or do I have a problem?
I am not aware of any other Box anywhere nearby.
S
 
Is this normal :censored: That tree is not looking too clever either. :cool:

Rip out. At root level.
 
We've tried that ^^ along with half a dozen other alternatives. The problem with Euonymus Japonicus is that it has a very upright growing pattern, so if you want to shape topiary balls or clouds for example. it can soon look very open at the sides. They claim it is slow growing (not necessarily a good thing if you want topiary) though we found it goes leggy quite fast. Personally I think Yew has worked by far the best for us, and is relatively easily grown from cuttings. Yew does not like getting its roots wet through winter though.

We have around 200 individual box plants and have lost only 2 (both established balls) since box moth arrived a few years ago. It's when people don't notice the early signs or leave it too late to take action that it becomes disastrous.
 
I am not yet at the stage of ripping out and starting again but my first thought about a replacement would be privet.
 
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