[SallyintNorth]

BH just came in telling me he'd been hearing about migrant moths attacking brassicas, and I thought of you...

Sounds like others are finding them this year linky

I just asked BH what else he could remember from the news article, and he said they are resistant to all known pesticides 

But the croprotect site says

Although there are insecticide resistance problems in other parts of the world, there is no evidence at present that the moths migrating into the UK each year are highly resistant to the insecticides approved in the UK for diamond-back moth control.

But then, they want to sell their insecticides, of course 

[in the hills]

It didn't give a description of them but heard on the news (radio) today that there was an influx of moths to southern England that was threatening the cauliflower and broccoli crops.

Thought of you FW!

[Fleecewife]

I think we can say that the moths have now been identified.  Now for remedies.  I never use chemicals in my gardens, so the fact that the usual chemical treatments don't work on the moths doesn't really matter to me.   I need an organic ie non-persistent-chemical, method to use.
I thought I would try wafting a cane with those yellow stick traps I so abhor, or thick grease on cardboard, on the tip.  This should mop up quite a lot of the moths.  They don't like people, but hopefully they won't jump so quickly into the air when it's just a big leaf thing coming for them.  It's worth a try. 
I will already be squashing cabbage whites on the leaves, so if I see any of this type of bug I shall launch into action, and wipe them all out    Hey Ho - my brassicas look so perfect this year too