Tiny, bright red specks, about 1mm across, sometimes move into buildings in large numbers. There are two species with several names, generally known as Red Spider Mites. Although they do no direct harm inside the house, if the mites are squashed they stain walls and decorations.
It is the female mites, also known as Clover Mites and Gooseberry Mites, which invade homes and other buildings in spring and autumn, climbing walls to seek egg-laying sites or places in which to hibernate.
According to entomologists male Red Spider Mites are “hardly ever found”, because the females lay their eggs parthenogenetically -ie. without the benefit of male involvement.
There are two species with different habits. Bryobia is dull red, moves slowly and feeds on plant sap; while Balaustium is bright red, runs quickly but erratically, feeds on pollen and lays its eggs in cracks in walls or the soil.
Correct identification is important – for if you grow grass around a building to discourage Balaustium, you may get Bryobia and if you put down concrete to discourage Bryobia, you are likely to get Balaustium!
REMEDY: Spray the affected walls and surfaces with an aerosol or a garden spray labelled for mite control. Cut back lush vegetation from around the walls.