Dust mites are not insects – they belong to the class of arachnids (like spiders). Dust mites reach adulthood within 3–4 weeks. Once mature, adult mites have a life expectancy of between 4–6 weeks, during which time females can lay between 40 and 80 eggs. With this fast reproduction rate, mites can colonise a new home within a year. Adult mites are roughly half a millimetre in size and have four pairs of legs.

House Dust Mite Allergy