Andrew M - as for bugs in the pitot tubes, here's a thought.
If the bug lodged in there before start up there is no way that the crew would have noticed until they started the take off run. Typically, ASIs do not read the first 30, 40, 50 kts etc (the one I use has a scale that starts at 60kt although the needle starts to move at 30). This is to stop the needle thrashing around on the ground in gusty conditions and wearing out the instrument.
I have never taxied fast enough to cause an ASI to read (although the Ryanair 737s taxiing at Prestwick may well do so!) and so that is the whole point of the ASI check during the take-off run (60, 80, 100kt depending upon the airline). If the ASIs do not match you reject - as seems to be the case here.