Mites, tiny arthropods related to spiders and ticks, are a common, often unseen, presence in many homes. These microscopic creatures are usually invisible to the unaided eye. While their presence can be unsettling, many mite species are harmless to humans. Some mites can cause issues like allergic reactions, particularly for sensitive individuals. Understanding how these organisms enter homes is key to managing their presence.
The Ever-Present Dust Mite
Dust mites, a prevalent type of mite, are an intrinsic part of nearly all home environments. Unlike larger pests, these tiny arachnids do not actively “invade” a home; rather, they exist wherever dust accumulates. They primarily feed on dead skin cells regularly shed by humans and animals, a food source abundantly available in household dust. A single gram of dust can contain thousands of dust mites.
These mites thrive in specific habitats where food is plentiful and conditions are favorable. Beds, mattresses, upholstered furniture, and carpets are common areas where dust mites congregate. Shed skin flakes, along with pollen, fungi, and feathers, provide their sustenance. Dust mites are a constant presence in most homes.
External Pathways for Other Mites
Beyond dust mites, many other mite species actively enter homes from external sources.
Pets and People as Carriers
Pets that spend time outdoors can inadvertently carry mites indoors on their fur or skin. Sarcoptic mites, which cause scabies in dogs, can transfer between animals and to humans through direct contact or contaminated bedding.
People can also serve as carriers, bringing mites into the house on their clothing or belongings after being in infested outdoor areas. Chiggers, primarily outdoor pests found in tall grasses, can be brought inside on clothing or pets. Once indoors, they might settle on furniture or bedding while seeking a host.
Structural Entry Points
Structural gaps in a home’s exterior provide easy entry points for various mites. Cracks around windows and doors can allow mites like clover mites to exploit tiny openings. Clover mites, which feed on outdoor plants, often migrate indoors during cooler autumn weather, seeking shelter. They can also climb siding and enter through openings into attics or upper levels.
Infested Items and Wildlife
Infested items brought into the home can also introduce mites. Flour mites, for example, are introduced through contaminated foodstuffs like flour, cereals, rice, or dried fruit. Used furniture or other second-hand items can also harbor various mite species. Mites associated with wildlife, such as bird mites from nests or rodent mites from within walls, can migrate into living spaces if their primary host leaves or its population grows.
Conditions That Encourage Mite Presence
Beyond initial entry, certain environmental conditions influence whether mites thrive and establish a lasting population.
Humidity
High humidity is a primary factor, as many mites, especially dust mites, absorb moisture directly from the air to survive. Dust mites flourish in relative humidity levels between 55% and 80%. Below 50%, they gradually dehydrate and die. Maintaining indoor humidity below 50% helps control mite populations.
Temperature
Temperature also plays a role in mite activity. Dust mites prefer temperatures between 68°F and 77°F (20°C to 25°C) for optimal growth. While high temperatures can be lethal, cooler temperatures slow their activity.
Food Sources
The availability of food sources beyond dead skin cells supports various mite species. Fungi and mold, often growing in damp conditions, serve as food for dust mites and are the primary food for mold mites. Organic debris, pollen grains, and bacteria also contribute to their diet.
Clutter and Ventilation
Clutter and poor ventilation create microclimates conducive to mite growth. Cluttered spaces offer more hiding spots and reduce air circulation, trapping humidity. Poor ventilation increases indoor humidity and warmer temperatures, providing an ideal mite environment.