Pest
Carrot flyBrown tunnels in carrots

Rusty brown tunnels in the roots. The leaves can turn reddish.
When it shows up: Late spring to autumn
What to do
Cover carrots with fine mesh straight after sowing, and keep it on.
Thin on a still evening: the smell of crushed leaves draws the flies.
Lift damaged carrots and use the good parts.
Helps prevent it
Not quite it?
These look similar. Compare the photos.

