Thistle stem gall fly
The thistle stem gall fly is a small fruit fly that lives on thistles. Its babies grow inside a round swelling on the thistle stem, a bit like a cosy little house. People even use it to help control weedy thistles.
How fast is it?
Fun facts
The mother lays between one and thirty eggs on the stem of a creeping thistle.
The larvae burrow into the stem, and the plant grows a lump called a gall around them.
The larvae spend the whole winter snug inside the gall.
In spring the young fly chews a tunnel and climbs out of the gall.
It was taken to North America to help stop creeping thistle from spreading.
Most asked questions about Thistle stem gall fly
?What is a thistle gall?
It is a swelling on the thistle stem where the fly's larvae live and grow.
?Is the thistle stem gall fly harmful?
No. It is harmless to people and is even used to help control weeds.
Myth buster
Myth: The Canada thistle gall fly comes from Canada.
Truth: No. It comes from Europe. It got the word Canada in its name because Americans call its food plant, creeping thistle, Canada thistle.
For bug experts
- Scientific name
- Urophora cardui
- Group
- Flies and mosquitoes
- Family
- Tephritidae
- Classification
- Insecta > Diptera > Tephritidae
- Lives on
- Europe, North America
- Also known as
- Canada thistle gall fly
Where the facts come from
- Urophora cardui (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 Pavel Kirillov from St.Petersburg, Russia. CC BY-SA 2.0, Wikimedia Commons. The sticker of this bug is drawn from this picture.
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