Autumn leaves
Oct. 27th, 2012 11:44 am![[personal profile]](https://www.dreamwidth.org/img/silk/identity/user.png){kind=small}
neverspentLast week, a friend brought me an oak leaf and wondered if I could identify the unusual, furry ball attached to it. I suspected it was an oak gall, but the kind I'm most familiar with are the smooth, tan-colored ones with red spots. Those are hollow in the middle with membranes of fuzzy material connecting the center to the outer shell. I've always assumed they're caused by some fungus or microbe.
Just a little research told me this fuzzy one was a woolly oak leaf gall. But what I also learned surprised me more: these galls and many other types, are caused by an insect! A tiny Cynipid wasp deposits her egg (oviposits) in the leaf, then the egg secretes growth hormones that cause the tree to create a chamber around the egg, a safe place for the wasp larva to develop. The gall itself is parasitic, but it doesn't harm the tree very much. Here's a great description of the Cynipids' life cycle, and there's a nice gallery of the wasps, galls, and larvae here. So fascinating. I love insects!
In less bizarre leaf news, the maple seedling I adopted and allowed to grow in one of my balcony pots several years ago is as tall as me now, and the leaves are changing rather dramatically this year.
Just a little research told me this fuzzy one was a woolly oak leaf gall. But what I also learned surprised me more: these galls and many other types, are caused by an insect! A tiny Cynipid wasp deposits her egg (oviposits) in the leaf, then the egg secretes growth hormones that cause the tree to create a chamber around the egg, a safe place for the wasp larva to develop. The gall itself is parasitic, but it doesn't harm the tree very much. Here's a great description of the Cynipids' life cycle, and there's a nice gallery of the wasps, galls, and larvae here. So fascinating. I love insects!
In less bizarre leaf news, the maple seedling I adopted and allowed to grow in one of my balcony pots several years ago is as tall as me now, and the leaves are changing rather dramatically this year.