I lifted up a chopping board from a kitchen work surface the other day and the underside was swarming with minute insects, probably about the same size as the dot on an i, if not smaller. It appears as if they may have dropped from a cupboard above but they were not in the cupboard itself but congregating on the inside bottom corner of the door. We wiped everything down but they keep appearing in the same places. Does anyone know what these might be and is there something like a spray that would get rid of them?