DES MOINES (AP) - Some wayward ticks have delayed a United Airlines flight from Denver to Des Moines.

The flight was delayed for six hours on Tuesday when passengers alerted flight attendants to three ticks in the cabin.

United spokeswoman Robin Urbanski calls it an "unusual situation," and that the airline regrets any inconvenience it caused to customers.

How the ticks got onboard is a mystery.

A replacement plane shuttled the 107 passengers to Des Moines, while the original flight was deticked and checked.

Urbanski says no ticks were found on passengers.