Nursery and Landscape - Leafminers to Watch For

The following is a report of two leafminers to watch for in the nursery and in landscapes from the University of Maryland.

Hawthorn Leafminer, (Profenusa Canadensis) and Birch Leafminer (Fenusa pusilla).

The red buds and serviceberry are in full bloom in central Maryland this week and we can expect two species of sawflies to emerge in the next week or so. We will see activity from adult hawthorn leafminers (P. canadensis) and the birch leafminers (F. pusila). The larvae of both species overwinter in the soil as pupae. When the two aforementioned trees are in full bloom the adults emerge from the ground. The adult females will cut a slit into the foliage and lay eggs between the leaf surfaces. The larvae feed in blotch mines between the leaf surfaces. We will see the splotchlike leaf mines show up in late May to June. There are multiple generations of both of these pests each summer.

Control: Soil applications of systemic such as imidacloprid (30 -60 days before leafmining activity. Dinotefuran (Safari) is reported to be uptaken much faster then imidacloprid.


Hawthorn leafminer damage. Photo from Whitney Cranshaw, Colorado State University, Bugwood.org

Birch leafminer damage. Photo by Whitney Cranshaw, Colorado State University, Bugwood.org.

Reprinted from the April 25, 2008 edition of the TPM/IPM Weekly Report for Arborists, Landscape Managers & Nursery Managers from the University of Maryland Cooperative Extension. Go to http://www.ipmnet.umd.edu/08Apr25L.pdf for the full report.