Ok we have inspected every inch of our terrace ceiling but have found no entry/exit holes nor evidence of any sawdust/powder residue nor any beetle activity. So I have to assume that the noise needs further investigation but it is NOT a result of the palm weevils who have posssibly been coincidental. The palm tree will have further investigation tomorrow & if the 'munching' noise reappears (nothing heard today) we will look into the terrace ceiling further-thankfully it is confined to the outside of the house. Thank you for all you info.