Knotting gall
The knotting gall is a small fly with a funny trick. Its larva lives at the tip of a fern leaf and makes it curl up into a messy knot, like a little mop. If you see a fern with a tangled tip, a larva may be hiding inside.
How fast is it?
Fun facts
The mother fly lays her eggs in fern leaves that are just starting to unroll in spring.
Usually only one larva lives in each knot, sometimes two.
When it is ready, the larva drops out of the knot and spends autumn and winter resting, then comes out as a fly in spring.
On one fern, scientists counted knots on nine leaves out of thirteen.
Most asked questions about Knotting gall
?What makes ferns curl into knots?
Often it is the larva of this small fly. It feeds inside the tip of the leaf, and the leaf curls up around it.
?Is the knotting gall fly harmful?
Not to people. It only lives on ferns.
For bug experts
- Scientific name
- Chirosia betuleti
- Group
- Flies and mosquitoes
- Family
- Anthomyiidae
- Classification
- Insecta > Diptera > Anthomyiidae
- Lives on
- Europe
Where the facts come from
- Chirosia betuleti (Wikipedia, CC BY-SA 4.0): what it looks like, where it lives, what it eats, sizes and fun facts, retold in simple words.
- Picture by Janet Graham. CC BY 2.0, Wikimedia Commons. The sticker of this bug is drawn from this picture.
If we got something wrong, sorry, we are bug fans, not a science journal. Tell us at [email protected] and we will fix it.
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