The Biological Relationship to Humans
Spider mites are diminutive arachnids, classifying them with ticks and spiders rather than insects. Their diet is strictly phytophagous, meaning they feed exclusively on plant matter, specifically the internal contents of plant cells. They use specialized mouthparts to pierce individual plant cells and extract the internal sap, making them a threat to hundreds of plant species worldwide.
The short answer to the question of biting is no: spider mites do not bite humans. They are species-specific plant parasites and cannot survive or reproduce on humans or animals. Their mouthparts, known as chelicerae, have evolved into needle-like stylets optimized for penetrating a plant’s cell walls. Human skin is simply too thick and structurally different for these tiny mouthparts to effectively pierce and feed.
A home infestation of spider mites is directly tied to the presence of houseplants or nearby vegetation. These mites do not seek out human hosts or materials like bedding or food sources. They may briefly hitch a ride on clothing or enter a home on an infested plant, but they immediately gravitate toward foliage. Without a plant host, spider mites will perish, confirming they pose no physical threat to people or pets.
When Mites Cause Skin Irritation
If a person is experiencing unexplained itchiness or small, bite-like marks, the source is almost certainly not a spider mite but another common household mite. The skin irritation often misattributed to plant pests is usually a reaction to other microscopic organisms. Properly identifying the cause of skin symptoms is important for effective treatment and to address any underlying health concerns.
House Dust Mites
One common alternative is the house dust mite, which feeds on shed human skin cells and thrives in warm, humid areas like bedding and upholstered furniture. Dust mites do not bite or sting, but their feces and decaying body parts contain proteins that can trigger allergic reactions. These reactions can lead to dermatitis, nasal congestion, or asthma symptoms in sensitive individuals.
Bird and Rodent Mites
Other mites, such as bird or rodent mites, may bite humans when their primary animal hosts abandon their nests or die. These mites are blood-feeders and will temporarily seek an alternative host, causing an itchy, red, and swollen rash. Their presence often signals a concurrent issue with a rodent or bird nest nearby.
Scabies Mites
Scabies mites (Sarcoptes scabiei) are highly specialized to humans and burrow into the outermost layer of the skin to feed and lay eggs. This causes an intensely itchy rash, typically presenting as pink, pimple-like bumps in skin folds. Unlike plant-feeding spider mites, these parasites complete their entire life cycle on the host and are highly contagious through close personal contact.
Controlling Plant Mites Indoors
Since spider mites are a plant problem, control measures focus on eliminating the pests from the infested plants. The first step upon discovering an infestation is to immediately isolate the affected plant to prevent the mites from spreading to other foliage. Because spider mites prefer hot and dry environments, increasing the humidity around the plant can help discourage their population growth.
A mechanical wash using water pressure is a simple, non-chemical solution. Indoor plants can be thoroughly sprayed down in a sink or shower to physically dislodge the mites and their webs, focusing on the undersides of the leaves where they congregate. This process must be repeated regularly, often every few days, because the treatment may not kill all the eggs, allowing new mites to hatch.
For further treatment, horticultural oils like neem oil or a mild soap solution can be applied to the entire plant surface. Neem oil works by interfering with the mite’s life cycle, while insecticidal soaps and rubbing alcohol solutions work by smothering or dehydrating the mites on contact. Applying any treatment thoroughly and consistently for several weeks is necessary to interrupt the rapid life cycle.