Birch Leafminer—Fenusa pusilla

Birch is host to a number of leaf-mining sawflies. Two of the more common miners are Messa nana (Klug) and Fenusa pusilla (Lepeletier). 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
The adult sawfly is a small, 1/4 inch long, black, fly-like wasp.

birch leafminer larva
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.

leaf damage caused by birch leafminer
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.

Click on images to view full-size

Identification and Control Information

More Information

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