flea beetles help needed please

[Crystalmoon]

Hi everyone, I am growing all my veg organically at my allotment & despite making raised beds with fresh growbags as soil & keeping the crops I planted completely covered by fleece the flea beetles have had a feast :'( Im assuming its them as I have millions of tiny holes in my pak choi leaves. They were fine up until about a week ago so Im wondering if the flea beetles invaded while I was weeding under the fleece?
How do you think they got in?
Is there anything I can do to deter them & still have organic veg? 
Thanks for any help & suggestions

[Crystalmoon]

[jennym]

Looks like your fleece didn't work this time, usually it's quite effective, I think that fine enviromesh is a good investment as well, because you can use it time and again, it's so sturdy.
Some say that home-made garlic spray helps to deter them. Basically it's crushed garlic cloves, steeped in water, then strained and mixed with a little veg oil. I would imagine there are other recipes too.

[Crystalmoon]

Thanks for your suggestion jennym Im thinking of sowing more veg that flea beetles are partial to so I will definitely try the garlic spray along with the fleece this time