Linden wart gall midge

There are 312 species of Contarinia worldwide. Adults are very small, 1⁄32″ (1.25 mm) long, and impossible to identify in the field. These midges are best identified by by the shape of the galls they produce and the plant species on which they are found.

Linden wart gall midge is a specialized plant feeder. It is found in the United States from New Hampshire to Minnesota, south to New Jersey and Iowa, and in New Brunswick and Ontario, Canada. In Minnesota it can be found on American basswood and littleleaf linden. The galls appear on leaves in the spring. They are small, round, wart-like or beebee-like, and raised on both the upper and lower leaf surfaces.

Total length: 1⁄32″ (1.25 mm)

Lime nail gall mite (Eriophyes tiliae) creates slender, raised, finger-like galls on the upper leaf surface.

American basswood and European lindens

Mature larvae drop to the ground and overwinter in the soil. Adults emerge in the spring.

In Minnesota, American basswood and littleleaf linden.