DESCRIPTION
Adults are black sawflies 2 to 3 mm long. The flat yellowish-white larvae, about 6 mm, are seldom visible.

DAMAGE
Larvae tunnel between the leaf surfaces, producing irregularly-shaped brown lines or blotches. Leaves of severely affected trees appear scorched by fire. Grey, white and paper birch are most affected.

LIFE CYCLE
Pupae overwinter 2 to 5 cm below the soil surface. Adults emerge in spring when leaves are half grown. They hover over birch trees, laying one egg per leaf, usually near branch tips. Eggs soon hatch and larvae mine the leaf for 10 to 15 days. Mature larvae then cut a hole through the leaf, drop to the ground where they pupate for 2 to 3 weeks. There are 2 to 4 generations per year.
CONTROLS

• If practical remove affected leaves by hand. Plant Black,
European or River birch to prevent leafminer damage, as they
rarely feed on these species.
• Inspect tips of birch branches for sawflies when leaves are about
half open. If insect is present, applying contact pesticides can
help reduce numbers.
• If sawflies are present or if there was leaf miner damage last year apply a systemic pesticide when leaves are half open. Young larvae are the most vulnerable stage of the insect.
• Keep a pest journal for next year including severity of damage,
controls used, and when you first noticed pest.

PESTICIDES
• Chemical-Diazinon or Malathion at label rates (contact
pesticides).
• Cygon 2E as a trunk paint treatment (systemic pesticides).
• Alternative-Safer’s Soap, Trounce or Summer Oil at label rates
(contact pesticides). (to print, right-click on this page)