White Insects on Wall ?

Hi, We arrived back in Lanzarote after being away for a couple of months due to lockdown and as you can imagine everywhere was full of dust etc. so we spent the day washing everything down. The next morning on one of the outside walls of the patio clusters of small insects had appeared and they are also on the wooden roof of the patio and legs of the outside furniture. We have never seen them before. Has anybody any information as to what they are and how to get rid of them ? They don't seem to move during the day but overnight the clusters have moved. Any advice welcome.