Sources of House Dust Mites
House dust mites are most abundant in bedding, upholstered furniture, wall-to-wall carpeting, and soft toys—locations where exfoliated human skin cells accumulate, which serve as the mites' principal food source. 1
Primary Food Source and Habitat Locations
Human skin cells (dander) constitute the primary food source for house dust mites, particularly species Dermatophagoides farinae and D. pteronyssinus. 1, 2
Mites concentrate in areas where skin shedding is greatest:
Critical Environmental Conditions That Support Mite Growth
Humidity Requirements
- Dust mites require relative humidity ≥50% to reproduce; optimal reproduction occurs at approximately 85% RH. 1, 2, 3
- At humidity levels below 50%, active mites survive only 6-11 days. 4
- Mites extract water vapor directly from unsaturated air at humidity levels above 65-70% to maintain their 70-75% body water content. 4
Temperature Preferences
- Optimal temperature for population growth is approximately 28°C (82°F). 3
- In actively used mattresses, feeding mites prefer temperatures of 32-36°C (90-97°F) with humidity between 55-59%, staying as close as possible to the resting human. 3
Modern Construction and Household Factors That Promote Mite Proliferation
Recent changes in home construction have created ideal environments for dust mite growth: 1, 2
- Enhanced energy efficiency leading to reduced ventilation and increased indoor humidity 1, 2
- Wall-to-wall carpeting throughout homes 1, 2
- Furnished basements in humid environments 1, 2
- Laundering with water temperatures <130°F that fails to kill mites 1, 2
High-Risk Construction Features
- Carpeting installed over concrete slabs inevitably becomes contaminated with both mites and fungi due to condensation-driven moisture accumulation and should be avoided. 1, 2
Geographic Distribution
- D. pteronyssinus and D. farinae are found in virtually all homes except those in arid or semi-arid climates and at high altitudes, where low ambient humidity limits their presence. 2
- Mite density in tropical regions like Malaysia and Singapore is greater than in temperate countries. 5
Allergen Dispersion Mechanism
- Dust mite fecal pellets become airborne when reservoirs are disturbed (vacuuming, foot traffic, making beds) but rapidly settle once disturbance stops. 1, 2
- Ordinary vacuuming has little effect on mite allergen concentrations because pellets easily pass through low-efficiency vacuum bags and become widely dispersed. 1
Common Pitfalls in Understanding Mite Sources
- Feeding rate and allergen production increase directly with relative humidity—mites feed, multiply, and produce more fecal matter at higher humidity levels. 4
- Mites can survive extended dry periods by forming desiccation-resistant protonymphal stages that persist for months at low humidity. 4
- Even new "hypoallergenic" mattresses and pillows become colonized within weeks and require encasing. 1