Boxwood Leafminer Fact Sheet

Fact Sheets > Insect Fact Sheets > Boxwood Leafminer

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 become unattractive in appearance.

Plants Attacked

Both littleleaf boxwood, Buxus microphylla and Common Boxwood, Buxus sempervivens, are commonly attacked, but there is resistance found in individual varieties of both species. Common boxwood cultivars with reported resistance are ‘Handworthiensis’, ‘Pyramidalis’, ‘Suffruticosa’ and ‘Varder Valley’. Buxus microphylla var. japonica has also exhibited resistance to the boxwood leafminer.

Insect Identification

The eggs of the boxwood leafminer are white to transparent and can be seen by holding the leaf up to the light. The larvae are yellowish-white and approximately 1/8 inch long. The adult boxwood leafminer is an approximately 1/10 inch long, delicate, orange-yellow to red, gnat-like fly.

Boxwood leafminer larvae	Close-up of Boxwood leafminer larvae

 

Life History

Winter	The partly grown larvae of the boxwood leafminer over-winter within their mines in the leaves of the host plant.
Spring	The larvae grow rapidly as the weather begins to warm. In late April, when weigela blooms, 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, and the larvae commence feeding.
Summer	The larvae continue to feed and grow slowly. In Pennsylvania there is a single generation each year

 

Damage Symptoms

The larval feeding between the upper and lower leaves causes blistering and often discoloration.

Yellow blisters from early larval feeding	Raised areas caused by larval feeding

 

Management Options

 

Cultural	Selection of the more resistant varieties.
Biological	Unfortunately, there are few known natural enemies of the boxwood leafminer.
Mechanical	Pruning the foliage before adult emergence or after egg laying ends will reduce the overall population
Chemical	Application of insecticide when the weigela is in bloom will reduce populations. Control measures for boxwood leafminer in Pennsylvania

Download Printable Boxwood Leafminer Fact Sheet

---

Authored by:
Katherine Mazzey, Penn State Extension Program Assistant
Michael Masiuk, Extension Agent, Penn State University – Allegheny County

Sources
Boxwood Leafminer. Center for Integrated Pest Management. North Carolina State University. http://ipm.ncsu.edu/AG189/html/boxwood_leafminer.HTML

Boxwood Pests (1998).Branching Out Volume 5 No. 3 May 8.
http://branchingout.cornell.edu/BO5(3)/BO5(3)Feature.html.

Couch, Gary, J. (1996). Boxwood Leafminer. University of Massachusetts.
www.umassgreeninfo.org/fact_sheets/leaf_miners/boxwoodleafmin.pdf.

Day, E. (1996). Boxwood Pests. Virginia Polytechnic Institute & State University. Virginia Cooperative Extension.
http://www.ext.vt.edu/departments/entomology/factsheets/boxmite.html

d’Eustachio, G., M. Raupp, 2001, Resistance of boxwood varieties to the boxwood leafminer, Monarthropalpus flavus (Schrank)., Journal of environmental horticulture. Sept 2001. v. 19 (3) p. 153-157

Hoover, G.A. (2000).Woody Ornamental Insect, Mite, and Disease Management. Penn State College of Agricultural Sciences. pp.24. http://woodypestguide.cas.psu.edu

Hoover, G.A. (2001). Boxwood Leafminer. Department of Entomology. Penn State.
www.ento.psu.edu/extension/factsheets/boxwoodleafminer.htm

Johnson, W.T. & Lyon, H.H. (1976). Insects That Feed On Trees And Shrubs,
pp.204. Comstock Publishing Associates. Cornell University Press.