The likelihood of a blocked pitot depends on how industrious the local bugs are, but pitots blocked by insects are rare in temperate climates. It could be quite different in the tropics.
In this case we have pitots mounted on the fin to provide data to the STS, which leads to questions:
- Are covers mounted?
- Are STS pitots inspected pre flight?
Most likely a mobile platform would be needed.
Static ports are commonly covered for maintenance and testing. Aero Peru is just one example of how badly that can turn out in flight.
It's possible that the front pitot-static system was functional while the STS system was not, or vice versa. The confusion that might produce can only be imagined.
The tendency is that PF will believe his own airspeed over the others. It takes some serious CRM to work out which airspeed, if any, is the good one when one or more are bad.