Pandas are generally regarded as an enemy of Steve (AKA "Nature's Most Evil Creature"). The first encounter with pandas was in Comic 24, where it is immediately apparent that Steve has nothing but hatred for the panda in the zoo. As a matter of fact, it seems as though Steve has a vendetta against the panda.
The next encounter between the pandas and Steve occurs in Comic 38, when the poison from a bee sting causes Steve to hallucinate that Beaver is a panda. A fight ensues. No pandas show up until Comics 65, 66, and 67 when the Shoe Goblin's pet panda threatens the existence of Beaver and Steve.
In the "Star Trek"-parody of Comic 74, "Beavock" and "Captain Steve" encounter the "Pandarians."
The largest encounter yet with pandas began with "Panda-monium - part 1" in Comic 113 and ended with part 6 in Comic 119. The 'diplomacy' enacted by Steve was arguably the largest victory against pandas.
Pandas go MEW. A lot.