The boxwood mite, Eurytetranychus buxi, is a common spider mite that specifically targets boxwood plants. This pest causes significant aesthetic and health damage. Since the mites are extremely small, recognizing the distinct signs of their activity is the primary way to manage infestations.
The Mite’s Physical Characteristics
Adult boxwood mites are minute, typically measuring around 0.5 millimeters in length, making them about the size of a period in standard newsprint. This tiny size means that magnification, such as a hand lens, is usually required to see the actual pest clearly. The body is oval-shaped and they possess eight legs, which distinguishes them from six-legged true insects.
Their color can vary, presenting as yellowish-green, reddish, or tan, and sometimes gray with pale legs. Some mites may also exhibit two large, darker patches on either side of their bodies. They may have a somewhat spider-like appearance with long front legs.
The life cycle begins with eggs, which are laid on the boxwood leaves, often overwintering there. These eggs are small and spherical, described as yellowish-ochre or light yellow, changing to a darker yellowish-brown as they mature. The eggs are sometimes flattened on top and are often found on the underside of the leaves.
Identifying Mite Activity
Since the mites themselves are difficult to see, the symptoms of their feeding are often the first indication of a problem. Boxwood mites damage the plant by piercing the leaf tissue and sucking out the chlorophyll-rich contents, a feeding action that also involves the injection of toxic saliva. This feeding results in a pattern known as “stippling,” which appears as tiny, light-colored spots on the leaves.
The stippling presents as minute white, yellow, or bronze flecks, sometimes resembling fine scratches or linear streaks. The boxwood mite does not produce visible webbing on the foliage. Heavy feeding causes the foliage to take on a grayish, silvery, or bronzed appearance due to widespread chlorophyll loss. In severe infestations, this discoloration leads to premature leaf drop.
Where and When to Find Them
The boxwood mite, Eurytetranychus buxi, is a common pest wherever boxwoods are grown. They feed actively on both the upper and lower surfaces of the leaves, though overwintering eggs are predominantly found on the undersides of the foliage.
The mites are most active during the cooler periods of the growing season, typically late spring and early summer. Overwintering eggs usually hatch in mid-spring (April or May), and the mites immediately begin feeding on new growth. They can have multiple generations per year, but the most noticeable damage occurs early in the season. Activity may slow during peak summer heat but can resume in the late summer or fall.