Warback
Frae Wikipedia
The warback (Aestrus bovis) is a lairge flee that leeves on kye an deer.
The flee liggs eggs on the foreleg o the afflictit kye. Thir will be etten by lickin, an be swallaed. The egg syne gaes throu the oesophagus muscles an spinal cord afore comin oot unner the skin.