By Barbarak
North Yorkshire,
United Kingdom 
Is this flea beetle damage to my Bowles mauve and a variagated yellow erysimum? I have other varieties which are also affected. It seemed to happen only after I had trimmed off the old flower heads. If it is flea beetle then will an insecticide work. Thanks you
7 Jul, 2016
Answers
I've also had cabbage loopers attack mine.
7 Jul, 2016
My first thought was flea beetle, especially as erysimum is a member of the family Brassicaceae (cabbage), and flea beetle often appear on these plants. My recollection of flea beetle is that they perforate the leaves along the edges. Now I will go along with Snoopdogs thoughts of leaf miner damage but they have since long gone.
8 Jul, 2016
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Well whatever it is, I've got the same on my Erysimum this year, but its said, if its flea beetle, agitating the bush should cause them to become visible because they jump, and I'm not seeing that on mine, but I think I'll spray it anyway as if it is that. Info on treatment and generally here
https://www.rhs.org.uk/advice/profile?PID=510
7 Jul, 2016