Information about cedar leafminer complex (various species), a group of defoliating insects found in Ontario.
- Native to North America.
- Cedar leafminer complex is a group of insects that feed on cedar foliage, causing a yellowing of the leaves.
- The group includes:
- brown cedar leafminer (Coleotechnites thujaella)
- cedar leafminer (Argyresthia aureoargentella)
- cedar leafminer (Argyresthia canadensis)
- arborvitae leafminer (Argyresthia thuiella)
Cedar leafminers feed on eastern white cedar (Thuja occidentalis).
Characteristics and life cycle
- Four closely related species feed within the leaves, hollowing out the leaflets.
- Damage can be seen early in the season and can be confused with winter browning.
- Adults are small white moths which emerge during June and July.
- Eggs are laid in July and August and larvae over-winter in leaflets.
- It is not uncommon to find all four species in a single location.
- Repeated attacks over several years can cause twig death and sometimes stem death.
Symptoms and damage
- Leaflets gradually become discoloured, from yellowish to brown in colour.
- Twigs become bare in the autumn as damaged leaflets fall off.
- Damaged leaflets can be held up to a light and tiny caterpillars can be seen feeding in the tunnels.
Ornamental trees may become infested. Twigs can be pruned during the winter to prevent spread.