# Oak apples - Keila

- By: Ivar Leidus
- Date: 2022-06-03
- Classification: Photograph
- Museum: [Wikimedia Commons](https://commons.wikimedia.org/wiki/File:Oak_apples_-_Keila.jpg)
- Rights: [CC BY-SA 4.0](https://creativecommons.org/licenses/by-sa/4.0)
- Picture: https://invisiblenetwork.ai/thumbs/commons/thumb/d/d8/Oak_apples_-_Keila.jpg/1920px-Oak_apples_-_Keila.jpg
- Who can see it: Kids profiles and older (museums give no ratings; placed by Invisible Network from the museum's own words)

Oak apples or galls (Ø 7–8 mm). Keila, Northwestern Estonia. Galls are made of plant tissue and form when an insect secretes a chemical that causes interference with normal plant cell growth. Adults lay eggs in expanding tree buds and leaves in the spring. The gall provides a safe home as well as food for the young wasps. Each gall contains only one young wasp. The larvae then feed, pupate and emerge from the gall as adult wasps after 2–3 months. Fortunately, galls do not cause significant damage to trees.