At 1–1,5mm this is one of our smallest native Ladybird beetles (in Western Europe).
Various authors still use different names, either Stethorus punctillum or Stethorus pusillus, so I've named one image each accordingly ;o)
Hence, collage of same beetle:
''Stethorus punctillum'', known generally as the lesser mite destroyer or spider mite destroyer, is a species of lady beetle in the family Coccinellidae. It is found in Africa, Europe & Northern Asia , Southern Asia, and North America.