A red cedar cone midge, Phytophaga thujae Hedlin

Damage: Mature infested cones are usually smaller than uninfested cones. Damage is visible externally after larvae have fed for a few weeks.

Hosts: Western red cedar

Exterior damage becomes more noticeable when larvae have been feeding for a few weeks. The scale margins split and turn brown. This damage is accentuated in mature infested cones which are often smaller than normal cones. Tissues inside the cone become darkened wherever feeding has occurred.

Cone-Gall Midge
Cupressatia thujae

Galls are composed of slightly enlarged cone scales and measure 7 mm high by 5 mm in diameter. In fall, galls are beige-green, often with black tips on each cone bract.

"Mayetiola" thujae

Damaged cones may be smaller than normal but not otherwise conspicuous
Seeds rarely survive an infestation.

Host: Thuja pilcata, western red cedar
Distr: British Columbia to Oregon