Arborvitae Leafminer
Argyresthia thuiella |
| USDA Forest Service. 1979. A guide to common insects and diseases of forest trees in the northeastern United States. Northeast. Area State Priv. For., For. Insect and Disease Management., Broomall, PA. p. 123, illus. |
This insect mines the scale-like leaves of northern white cedar (arborvitae). As the larvae feed on and excavate the tissue between leaf surfaces, individual leaves or groups of leaves at the tips of branches become yellow or brown. Leafminer injury can be distiguished from browning due to other causes by holding a leaf to the light; with leafminer injury, the leaf will appear translucent. The larvae themselves may be seen in the mines in late summer or early spring by holding a leaf to the light and probing the brownish area to make the caterpillars wiggle. The mined leaves give the tree a sickly and unsightly appearance; the greatest damage is to ornamental plantings.
Arborvitae leafminers overwinter as immature larvae in the leaves. In late April and early May the larvae are feeding, and pupation occurs in May. The adult moths, which appear from mid-May through June, are light gray, with an average wingspan of 3/8 inch. They wedge their eggs between the tip of one leaf scale and the base of an adjoining one. On hatching, larvae enter the leaf. Most moths have laid their eggs and died by July 1. There is one generation per year.
Larva(e); Caterpillars are only 1/5 inch long when full grown.
John A. Weidhass, Virginia Tech |
Damage
Connecticut Agricultural Experiment Station Archives, Connecticut Agricultural Experiment Station |
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