Missing pins of 16F887 in Proteus 8 schematic
These are the power and ground pins, VDD and VSS. How else did you think the IC would get power? I don't know Proteus, but there are likely on a separate logical part of the same device, a separate power block for the schematic capture which allows for putting all the power inputs for an entire schematic in the same place. This avoids the mess of having decoupling caps &amp; power nets cluttering up the signal flow across the schematic.