**Rat Mites / Rodent Mites** (*Ornithonyssus* spp., *Laelaps* spp.) are obligate parasitic mites that feed on the blood of rodents (rats, mice) or birds. The most common human-biting pest is the **Tropical Rat Mite** (*Ornithonyssus bacoti*). The conflict is **skin irritation and nuisance**: when their primary host dies, is removed, or abandons the nest, these mites migrate aggressively into human areas and bite people (primarily for exploration, not sustenance), causing intense itching and papular dermatitis.
Taxonomy and Classification
Mites belong to the Class Arachnida (spiders, ticks) and the subclass Acari. They are not insects. They undergo simple metamorphosis (egg, larva, nymphal stages, adult).
Physical Description
Adults are tiny, less than 1\text{ mm} long.
- **Adult (Key ID):** Oval body shape; four pairs of legs; gray to reddish-black after feeding; often very difficult to see without magnification.
- **Behavior ID:** Mites are often seen crawling rapidly on walls, ceilings, and bedding once their host is gone.
- **Symptom ID:** Small, red, intensely itchy papules, often concentrated around the waist, neck, or wrists.
- **Conflict:** Public Health, Nuisance.
Distribution and Habitat
Found globally. Their primary habitat is the nest, bedding, and fur of rodents and birds; they migrate into structures when the host population crashes.
Behavior and Conflict
The conflict is a result of host absence.
- **Opportunistic Biting:** They will feed on human blood when a preferred host is unavailable, often inflicting multiple bites.
- **Host Dependence:** Control of the mite requires control of the host, as the mite infestation is secondary to a primary rodent or bird infestation.
Management and Prevention
Management is **Host Elimination and Acaricide**.
- **Eradicate the primary host** (e.g., trap and exclude rodents; remove bird nests) to stop the life cycle.
- Apply residual acaricide dusts or sprays to the areas of migration, particularly in wall voids and cracks near where the host nest was located.
Conservation and Research
Research focuses on the role of mites as potential vectors for emerging pathogens and improving integrated pest management strategies for companion animals and livestock.