Alder leaf beetle
The alder leaf beetle is a small, shiny beetle, black or metallic blue like a tiny jewel. It lives on alder trees and loves to munch their leaves. Its babies are black too, and they eat so much that the leaves end up full of holes.

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Fun facts
The holes in alder leaves from late April onwards are often made by its larvae, and the biggest larvae do the most munching.
The grown-up beetles sleep through the winter and wake up again in spring.
It has only one family of babies each year.
In Britain people thought it had disappeared, but in 2004 it was found again in Manchester and now it is spreading.
Most asked questions about Alder leaf beetle
?Is the alder leaf beetle harmful?
Not to people. It eats alder leaves, but the trees can usually cope with the damage.
?What does the alder leaf beetle eat?
Mostly alder leaves, and sometimes hazel, birch or hornbeam leaves when food is short.
?How big is the alder leaf beetle?
It is about 6 to 7 millimetres long, smaller than a fingernail.
For bug experts
- Scientific name
- Agelastica alni
- Named by
- Linnaeus, 1758
- Group
- Beetles
- Family
- Chrysomelidae
- Classification
- Insecta > Coleoptera > Chrysomelidae
- Lives on
- Europe, Asia, North America
Where the facts come from
- Agelastica alni (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 Felix Grimm. CC BY-SA 3.0, Wikimedia Commons. The round sticker of this bug is cut from the same 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.