Make sure you have the Law or the RPG, and the M16, ration and supply marker. Wait until Pupa stops and fire a rocket at the large cylinder console on its front. Try to avoid the electric shots by moving. When it launches its lighting rods, take out a few near you with the M16 and lay flat on the ground until the lighting stops. Then, keep firing. If you are running low on rations and ammunition, use the supply marker to call in more. Once it is destroyed, fire a rocket at the hatch on top of its head. Take the "programs". It does not matter which ones you take out.