- Eggs: Females lay eggs on leaves where they hatch.
- Larvae: Larvae are whitish and may grow up to 6 millimetres long. They drop to the ground for pupation where they overwinter in the soil.
- Adults: Adults emerge in May. They are dark bodied, wasp-like and about 6 millimetres long.
- Stippled or dead areas on leaves: Larvae mine food from the leaves of the tree, resulting in a small dot or brown blotch on the leaf.
- Presence of larvae: See larvae when you hold an infected leaf up to the light.
- Preventive tools:
- Follow a regular watering, fertilizing, and pruning schedule to keep your trees as healthy as possible to resist attack.
- Rake fallen leaves and other organic material around the tree where the insect likes to overwinter.
- Physical tools: Not applicable
- Biological tools: Not applicable
- Least toxic chemical tools: Not applicable