Running Microbug by Velleman Inc.

The Running Microbug has two photoresistors, one left front an one right front, that sense the presents or absence of light. Two subminiature motors are used to move the "Running Microbug". The left photoresistor controls the right motor and the right photoresistor contols left motor. This allows the Microbug to seek light by always turning into light. But, of course, not helpful in the complete absents of light. The photoresistor conducts electricity when light is present or lowers resistance. Simply, turns the Microbug on and off. In addition, there are two variable resistors that can allow one to control the trim or speed of each motor. The red LED's work as indicators to the presents of light in respect to there photoresistor. Or, the flow of electricity to the motors.

Running Microbug
 

I got the Microbug put together and tested it in light and dark.