United Kingdom 
My rosemary bush is infested with little beetles which are munching holes in all the leaves, making them dried out and sticky so they are unsightly and unappetising. The beetles are rather less than a centimetre long and a pale metalic brown tinged with a greenish shine, with longitudinal fine stripes head to tail. What are they, will they harm the plant, and if yes, how can I control them, preferably organically?
12 May, 2015
Answers
You can spray them off with a jet spray from garden hose.
13 May, 2015
Thanks! I hadn't thought the RHS would be tracking this, but as it may help I'll certainly send them the info. Will try the hose blasting: sounds fun at least ;-)
13 May, 2015
I've had a real problem with these for the last couple of years. I diligently checked all the lavender plants, sage & rosemary twice a day and picked off and squigged all the beetles I found. Sometimes as many as 15. So far this year I don't appear to have any. But it's early yet! I do the same thing with Lily beetles.
13 May, 2015
Previous question
Sounds like Rosemary beetle. See https://www.rhs.org.uk/advice/profile?PID=555
for information. The RHS are asking people to send in records of this beetle. Sounds like it's quite a problem.
12 May, 2015