Brake lever worm

[MichaelW2]

My Shimano Tiagra 9 brake levers have strange-looking worm trails all over the metal. I think the metal has some kind of plastic film or coating and the trails are under the plastic . The worm trails are less than 1mm wide and wiggle all over the surface. WTF is it?

The bike has been in a shed for 2 years

 

[Citius]

Minor surface corrosion under the paint. Nothing to worry about. I have two sets of levers (Tiagra and Ultegra) which have both been like it for years.

 

[RedRider]

There's a number of bicycle parasites including bar tape worm and bottom bracket tick.

 

[Yellow Saddle]

There's a number of bicycle parasites including bar tape worm and bottom bracket tick.

Aha! This explains those ticking noises in most BBs.