Forest Pest Insects in North America: a Photographic Guide

Arborvitae leafminer

Argyresthia thuiella (Packard) Lepidoptera: Argresthiidae)

Orientation to pest

The arborvitae leafminer, Argyresthia thuiella (Packard), is a native North American moth that forms mines in foliage of eastern arborvitae (northern white cedar) trees (Thuja occidentalis L.) in forests and landscapes. This moth is found in eastern Canada and in the United States, south to Maryland and west to Missouri. It is also invasive in Europe. Adults fly in spring to early summer and adults lay eggs in the axils of branchlets or along the edges of leaves. Newly emerged larvae bore into the leaves and feed the rest of the year there as leafminers. Winter is passed as larvae in mines and pupation occurs in the mine. Adults emerge the following spring. Outbreaks in Maine have severely damaged arborvitae. Damage can also occur in nurseries or on landscape arborvitae.

Hosts commonly attacked

This caterpillar feeds on eastern arborvitae (northern white cedar) trees (T. occidentalis).

Distribution

The moth is found in eastern Canada and in the United States, south to Maryland and west to Missouri.

Images of arborvitae leafminer

Adult of arborvitae leafminer (moth wingspan is 8 mm) Petr Kapitola, State Phytosanitary Administration, Bugwood.org 768x512 / 1536x1024
Moth in natural pose Tom Murray 768x512
Mature larvae of arborvitae leafminer, removed from mine John A. Weidhass, Virginia Polytechnic Institute and State University, Bugwood.org 768x512 / 1536x1024
Close up view of damage on landscape arborvitae Robert Childs, University of Massachusetts, Bugwood.org 768x512 / 1536x1024

General view of damaged plant Robert Childs, University of Massachusetts, Bugwood.org 768x512 / 1536x1024
Figure 1. Adult of arborvitae leafminer Argyresthia thuiella (moth wingspan is 8 mm); right, moth in natural pose Figure 2. Mature larvae of arborvitae leafminer, removed from mine
Mined (brown) arborvitae foliage Connecticut Agricultural Experiment Station Archive, Connecticut Agricultural Experiment Station, Bugwood.org 768x512 / 1536x1024
View of larvae in mine (cut away) Robert Childs, University of Massachusetts, Bugwood.org 768x512 / 1536x1024
Arborvitae leafminer pupa John A. Weidhass, Virginia Polytechnic Institute and State University, Bugwood.org 768x512 / 1536x1024
Figure 3. Mined (brown) arborvitae foliage; right, view of larvae in mine (cut away) Figure 4. Arborvitae leafminer pupa Figure 5. View of damage on landscape arborvitae, top, close up; bottom, general view of damaged plant

Important biological control agents related to this pest species

In Canada, natural control of arborvitae leafminers is provided by the widespread parasitoid Pentacnemus bucculatricis Howard and also by Apanteles bedelliae Viereck. Some 26 species of parasitoids are known to attack this leafminer.

Web links for information on arborvitae leafminer

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