M.exigua causes galls on the root system, which are visible with the naked eye.

The host plants for the larva are Hawksbeard, Cat's ear and Sow-thistle flower heads, causing galls to form.

One form produces galls on the leaves and twigs, another affects the roots, causing galls or swellings, and often killing the vine.

It is a plant parasite, causing galls or other damage to the plant tissues.

Vasates is a genus of mites in the family Eriophyidae, which cause galls on the leaves of trees, including, among others, the following species:

Root knot nematodes (Meloidogyne species) can cause stubby or forked roots, or galls.

Some insects cause galls.

The larvae of most species feed internally on various parts of their host plants, sometimes causing galls.

It is vulnerable to the fungal plant pathogen Erythricium salmonicolor, which causes galls and the dieback disease known as pink limb blight.

They typically cause galls on their plant hosts.