Rosemary Beetle on rosemary and Lavender?

The rosemary beetle eats the shoot tips and flower spikes, causing most damage from late summer until early summer.  Look out for the stunningly pretty adult beetles (about 9mm long, metallic dark green with five purple stripes on each wing case) and also the larvae (soft-bodied, grey-white grubs measuring up to 8mm in length).  Both are rampant feeders on their host plants.
The rosemary beetle became established in the UK in the 90's and if the infestation is heavy, it can do a lot of damage.  Try picking as many adults and larvae off the plants as possible and this might do the trick.  Alternatively you could spray with a insecticide such as one containing pyrethrum.