| Most definitely a bug can cause a short. The higher the voltage along his path, the more likelihood. This was a real problem back in the days of vacuum tube-based computers; a moth or roach would get inside the rack, come across one tube's B+, and take out one or two digital bits, resulting in a wrong answer. Non-tube amps today don't need to supply plate voltages but they still can supply a couple dozen or more volts per rail -- plenty to "green mile" a critter. Once fried, the bug's body loses its water content, and therefore its low electrical resistance. | 
