Argyresthia thuiella

Arborvitae leafminer

Description

Argyresthia thuiella, commonly known as the arborvitae leafminer, is a moth species (Argyresthiidae) primarily affecting thuja Thuja occidentalis. However, it can also infest other species within the Thuja genus and Chamaecyparis species. Adults are small, light-gray moths with brown and black spots, laying eggs from June to July on the twigs of a host plant. The larvae, greenish-brown with a dark head, feed within the foliage (branches), leading to browning and dieback of leaf tips. This damage is usually visible during the winter and can often be mistaken for other causes. In Europe, A. thuiella has established in many regions a strong populations, especially in urban landscapes and ornamental plantings where its host plants are prevalent.

Symptom

Infestation signs include brown, hollow leaf tips with visible entrance holes and frass, appearing mostly in spring and fall on the plant's sunniest side.

Tree Species: Cypress, Thuja

Part of a plant- attacked: Leaf / Needle, Branch

Pest significance: Harmful

Pest Category: Insects

Invasive Species: No

Present in EU: Yes