Boxwood Leafminer Diagnostic Guide
Boxwood leafminer, Monarthropalpusi flavus (Schank) is native to Europe and widely distributed throughout the United States. Its introduction dates back to the same time period that common boxwood was introduced into this country. The leafminer causes serious damage to boxwoods, with heavily damaged plants becoming unattractive in appearance.
Shrubs at Risk
All boxwoods are susceptible, but more slowly growing English varieties are less susceptible than American varieties. Commonly infested plants include littleleaf boxwood and common boxwood.
Signs of Damage
- Boxwoods infested with this leafminer develop blisters on the lower leaf surface.
- Infested leaves are usually smaller, off-color and drop sooner than healthy leaves.
- Heavily infested boxwoods usually have sparse foliage and poor color.
- The partly grown larvae overwinter within their mines in the leaves of the host plant.
- The larvae grow rapidly as the weather begins to warm. In late April, they turn into orange-colored pupae and emerge as a fly.
- After mating, the female inserts her eggs deep into the leaf tissue. She dies soon after and the eggs hatch approximately 3 weeks later.
- One generation per year.
Since boxwood leafminer is an early spring insect, soil applications must be done late in the previous growing season, or very early in the current growing season, to obtain acceptable control. Xytect™ and Transtect™ are effective soil applied or foliar spray solutions.
Soil applications are extremely effective against this pest. Xytect™ and Transtect™ can be applied as foliar sprays. Transtect™ will provide translaminar movement and good control if the optimal application window for soil applied products is missed. For small to medium size shrubs or hedges consider using lower dosage rates.
A Diagnostic Guide is designed to help you identify a pest issue and management solutions. Always refer to product label for all rates and approved uses. Some images courtesy forestryimages.org. Use of the images does not imply endorsement of treatments by forestryimages.org