The term “red mite” does not refer to a single species but rather a diverse group of small, reddish arachnids from the class Acari. While they share a reddish body color, their survival strategies and food sources are extremely varied. A red mite encountered in a garden, a chicken coop, or on a houseplant will have a completely different diet. Understanding what these different species consume is the first step in identifying them and the threat or benefit they represent.
Diets of Plant-Feeding Red Mites
The most frequently encountered red mites are the phytophagous species known as spider mites, such as the European red mite (Panonychus ulmi). These mites possess specialized, needle-like mouthparts used to pierce the outer layer of plant leaves. Their feeding mechanism involves extracting the liquid contents of individual plant cells, specifically targeting the chlorophyll-rich mesophyll cells. The removal of this chlorophyll and sap causes the characteristic damage seen on infested plants.
When these mites feed, the damaged leaf cells die, resulting in a visible pattern of tiny, pale spots known as stippling. Extensive feeding can cause the entire leaf to take on a bronzed, yellowed, or silvery appearance, particularly on houseplants, vegetables, and ornamental plants. The European red mite is a common pest of fruit trees and woody ornamentals. The two-spotted spider mite, which turns reddish-orange when overwintering, feeds on over 1,100 different plant species. These mites require the constant consumption of cell contents to fuel their rapid development and reproduction.
Blood Meals: The Feeding Habits of Parasitic Red Mites
A completely different dietary strategy is adopted by parasitic species, whose diet is strictly hematophagous (feeding on blood). The poultry red mite (Dermanyssus gallinae) is a prime example, posing a threat to birds and poultry operations worldwide. These mites are ectoparasites, living on the exterior of a host, but they are intermittent feeders rather than permanent residents.
The poultry red mite spends the majority of its life cycle hiding in crevices, cracks, and litter away from the host. They emerge primarily at night to take a quick blood meal, which causes an engorged mite to appear bright red. Blood is mandatory for female mites to develop eggs and for the protonymph and deutonymph stages to progress. While their preferred hosts are birds, these mites are not strictly host-specific and have been known to bite and feed on mammals, including humans. However, they cannot sustain a population on human blood alone.
The Unique Consumption of Clover Mites
The clover mite (Bryobia praetiosa) is often mistaken for a spider mite but has a distinct and narrow diet. These mites are herbivores that feed on the sap of a specific range of low-growing vegetation. Their primary food sources include moss, clover, algae, and succulent lawn grasses. Clover mites are attracted to areas with lush, nitrogen-rich turf growing against a building foundation.
When outdoor conditions become too hot or too cold, clover mites seek shelter, often invading homes in massive numbers. They do not feed on household goods, clothing, pets, or people once inside. Their diet is strictly external, and mites found indoors are simply seeking a more suitable environment for survival or overwintering. They will not reproduce or sustain themselves without access to specific outdoor plant food sources.
Beneficial Red Mites and Their Predatory Diets
Not all red mites are pests; some are beneficial, with diets consisting entirely of other arthropods. Predatory mites, such as Phytoseiulus persimilis and Amblyseius fallacis, are commercially raised and utilized in agriculture for biological control. Their color often varies from pale yellow to orange-red, depending directly on the color of their recent prey. They actively hunt and consume pest species, primarily plant-feeding spider mites.
These predators use their mouthparts to pierce their prey and suck out the internal fluids, effectively killing the pest. Some predatory species, like Typhlodromus pyri, are omnivores, supplementing their diet of pest mites with pollen, fungi, and other small insects when pest populations are low. This varied diet allows them to remain in a crop environment even when their primary prey is absent, providing a natural and sustained defense against future pest outbreaks.