As the aircraft was being taxied for take-off, the nosewheel struck a small termite mound. The nosegear was broken off and the aircraft came to rest on the lower engine cowl. The strip was normally slashed every two weeks, a process which cut the grass and removed termite mounds. Because of recent dry weather which had inhibited grass growth, slashing had not been done for 4-5 weeks, and small termite mounds had built up. Several of these mounds were not noticed during the pre-flight strip inspection. The low colour contrast between the mounds and the strip surface, and the sun angle at the time, made the mounds difficult to see.