Something is attacking my Lettuce!

[WiZeR]

Not only do I have a Blueberry assasin, my lettuces are also getting a beating. I didn't take a picture, but precisely 2 rows are being eaten alive. Lots of little holes and on closer inspection there where tiny dark coloured bugs all around. The rows are all under a cloche and the 2 affected rows are called 'Oriental Mix'. The other varieties are completely uneffected. I wasn't sure what to do so I removed the cloche from the affected rows.

What is eating my lettuce? and what can I possibly do?

Any help or advice much apprecieated.

[Tigs33]

Sounds like flea beetles, do they jump around a lot??

I think you can sprinkle some derris on them to get rid of them

[WiZeR]

yes they were jumping like fleas, what is derris?

[dwrudd]

Derris dust is a white powder that can clear all sorts of pest but is indiscriminate and kills all crawling insects. I do use it spareingly and it is very effective. Most good garden centres will have it.

Darren