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Home > Bugs > Bugs of Trees and Shrubs > Birch Leafminer

Birch Leafminer—Fenusa pusilla

The birch leafminer, Fenusa pusilla, is a small sawfly native of Europe that was first detected in Connecticut in 1923. It has since spread throughout northeastern North America. It attacks all varieties of birch trees (betula spp). The name "leafminer" is derived from the larval habit of feeding, or mining, the plant tissues between the upper and lower surfaces of birch leaves.

birch leafminer adult birch leafminer larva leaf damage caused by birch leafminer
The adult sawfly is a small, 1/4 inch long, black, fly-like wasp. The small, white and slightly flattened larvae of the birch leafminer live within the birch leaves. They can be easily seen when the leaves are held up to the light. Damage to the leaves of the host plant initially consists of small individual leaf mines; however, as these overlap forming larger blotches, wilting and gradual leaf death occurs.

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[Photos, left to right: Cheryl Moorehead, individual, Bugwood.org; Joseph O'Brien, USDA Forest Service, Bugwood.org; Whitney Cranshaw, Colorado State University, Bugwood.org]

 
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