Cynipidae

Cynipidae is a family of small wasps in the order Hymenoptera, commonly known as gall wasps. They induce the formation of galls on plants, especially oaks.

The life cycles are often specialized and host-specific. Female wasps lay eggs in developing plant tissue; the larva secretes compounds that manipulate plant growth, producing a gall that provides food and shelter. Galls vary widely, and many species exhibit alternating generations, with sexual and asexual generations producing morphologically distinct galls and adults. Some species produce only one reproductive form. Adults are typically a few millimeters long.

Cynipidae have a worldwide distribution, with greatest diversity in temperate regions. Oaks (Quercus) are the most common hosts, though smaller groups use other plants. Galls are highly species-specific, often enabling identification of the inducing wasp.

Galls host developing larvae and may be inhabited by parasitoids and inquilines; these interactions influence local arthropod communities and oak ecosystems. Taxonomy is complex, with many described species and many more likely undescribed, and modern studies increasingly use molecular data.