What was found
(CAN) PASSING THROUGH 3500 FT IN CLIMB , CAPTAIN AIRSPEED INDICATION BLED FROM 250 KNOTS TO 145 KNOTS AND STABILIZED, WHILE F/O AND STAND-BY AIRSPEED INDICATOR WERE STABLE AT 250 KNOTS. ACFT DIVERTED AND LANDED NORMALLY. INVESTIGATION FOUND THAT THE CAPT`S PITOT TUBE WAS CONTAMINATED WITH AN INSECTS. CAPTS PITOT SYSTEM WAS PURGES AND CLEARED. AS PRECAUTIONARY MEASURES, THE CAPT`S AIR DATA MODULE, ADM, WAS ALSO REPLACED. AIRSPEED SYSTEM WAS TESTED SERVICEABLE AND ACFT RETURNED TO SERVICE.