I know that it is too late for fhis year, so looking for suggestion for next…
We have a walnut tree in the garden which usually yields enough for the odd walnut cake and a years worth of home made muesli.
This year it feels like we are losing a lot more to the husk fly. Most are starting to blacken where the fly has laid eggs and the larvae are eating the husk 
We usually leave the garden to do as it will, with a bit of tree pruning and cutting back of the shri6bs when needed. The husk flies have, however, got a bit too greedy.
What are you using to treat against these flies, and when do you apply it?
I would hope to avoid any really nasty chemicals. We have donkeys that use the trees as shade, owls perch there whilst hunting at night, the dogs find the trunk very interesting and our cat is, well , a cat. I don’t want to use anything that could be injurious to them, nor us for that matter 
This article may help as it talks about various trapping methods. Though it does say they are not necessarily bad every year. Do you need to do anything if all you want is a bit of muesli and the odd walnut cake?
https://www2.ipm.ucanr.edu/agriculture/walnut/walnut-husk-fly/
Thanks Sue, I found that article from the University of California too. It is interesting reading, although aimed more at the commercial side with orchards of walnut trees.
We only have the one, and I was hoping for suggestions of products available in the French or EU market. Also, the period of study is a bit onerous just gor the one tree This year is particularly bad; so far, 75% of the nuts are infested with the larvae. I can still feel my skon crawling from sorting through the last windfall. I am hoping for a simple means of reducireducing bng the losses, without spending a lot of money or time 
Have you got neighbours with walnut trees locally? I’d try asking them. I know my neighbour paints the trunks of his fruit trees in the spring to stop specific things getting on them, it is white and apparently natural. Failing that your local agricultural co-op or nursery should be able to help you.
Whitewash, helps stops insects boring into the trunk and sunburn (yes trees can get sunburn).
We have had great success it deterring cabbage white flies using nettle purin. I guess the disgusting smell confuses them into thinking it is not a cabbage. So one you know the flies are around you can try spraying the bits you cam reach to keep some of the crop safe.
Failing that make vin de noix and pickled walnuts instead as you have to harvest the walnuts mid July before they get damaged by fly.
Where are you based Martin @Magwych ? I ask as I’ve never seen / heard of them and then I just saw some fallen nuts on the way to the washing line with holes. I’m in the Dordogne. We have 3 big trees so would really like to find out how to stop this happening. And how to dispose of the effected nuts so as not to spread from year. Arrrggghhh I’ve already lost 2 fruit trees this year and have no idea why so I don’t need this as well.
Ahhh is it as simple as that!!! It looks cute too!
Thanks for the link Caroline. This was a worry though ’ vous pouvez pulvériser sur l’arbre un traitement bio naturel à base de Talc . Le talc va créer une barrière minérale sur les noix qui empêche les mouches de pondre à l’intérieur.’ as 2 of ours bust be at least 20m tall so no idea how we could do that!
Fascinating subject.
I found this article: https://gardenerspath.com/how-to/disease-and-pests/walnut-husk-flies/
It suggests two things to do: trap the flies (that’s about halfway down) when they appear and check whether the females are carrying eggs (or just squish them all, I suppose) and - perhaps - ensure that the infected walnuts, which will have fallen to the floor, don’t end up in the soil where the maggots can pupate.
I suppose you could put something down around the tree trunk, of the diameterof the tree itself, to catch the maggotty windfalls and then burn them?
I’m not speaking from any sort of experience, but as a lover of walnuts.
I think I’ll get a pic tomorrow and post it and see what you all think. This is our 5th year here and one of our previous houses had a walnut tree and never seen the holes I noticed today (due to this thread!).
I’m guessing that we have them in our garden, judging by some of the fallen nuts I picked up the other day, but as no one around here treats any of their walnut trees, and as our meager crop is very dependent on warm wet weather in the spring, I’ve not been too worried about it I imagine that in other climes, it would be more of an issue. I’ve not found any maggots in the husks themselves though, so perhaps that is a good sign ?
Yes, that will be whitewash, made from slaked lime.
It was very common in Cyprus, where we had a small house in a mountain village. There, they did it to keep the ants off the fruit. A 150mm wide ring around the circumference was apparently sufficient.
We have let infested nuts lay on the ground, we will.clear them this year. That may help keep the numbers down for next. I guess that the mild winters have kept the population up.
The larvae are very small, barely noticeable. Once you “get your eye in”, they become more obvious.
I don’t mind sharing the fruit and nuts with nature, normally. Once the flies have had theirs, the fox his part of the windfalls and the dormice theirs , there is not much left. If they fall too close to the fence line the donkeys snaffle them too.
In all the snaffling of walnuts, please remember walnuts can be poisonous to dogs and indeed fatal in some cases. Knowing of someone who lost their dog, I now rake ours up daily. The dangerous ones are those left on the ground to go mouldy.
Thank you @SuePJ, I did not know that. We will definitely rake them up. Stanlee is not that bright, he eats pretty much everything on the ground.
Get one of the walnut rollers. They look like a gimmic but they are absolutely brilliant. For example: https://www.manomano.fr/p/rouleau-ramasse-noix-chataignes-et-marrons-manuel-gris-alu-4824628 (you can find them cheaper too).
If anyone tells you they are unecessary, do you have a rice cooker? If not, ask someone with one why they need one when they can cook rice in a saucepan. Some devices are jsut meant to be.
@IanJ Thanks so much Ian, JUST what I need. Especially after all the wind and rain of the last couple of days. I’ve been meaning to post here and ask what to use - brilliant.
Just a PS though Ian? Tory? I note that the photo shows walnuts with no outer casing. But in fact what’s on the ground are the larger green cases with the walnuts still inside. Can it cope?
I don’t agree on the rice cooker 
but heartily heartily agree on the walknut collector. I thougt that was really cheap, MIL got us one but it was about GBP60 from memory. Life changer. Seriously we have 3 huge trees plus 1/2 of the neighbours huge tree and I have a pretty dicky back. It went from being a dreaded chore to quite an enjoyable one! I have a picture of one year doing it with a small toddler attached to my back in a sling as he wouldn’t be put down or left. I think that was the last year I picked them up
That site looks like it has some other fruit picking etc items. Never heard of them - has anyone used them?
With you on rice cooker…was given one by a friend as she didn’t think it worth while, and neither did I, so handed it on. Perhaps this rice cooker is still wandering the globe searching for a kitchen that will want it!
Yes ours can cope. I do try to run my foot over the ones with the pod thing still on as it then comes off really easily. I don’t get all of them, if they have gone black it doesn’t work. I then empty all the loads into bucket (you get a wire thing that you attach to the side so no bending even for this bit). Once the bucket is full I then sort into other buckets: 1. clean nuts 2. green husk nuts 3. Black ones. Often the blacks are fine inside but they dont’ keep so I open and use / freeze them first.