Frogs fell from the sky. Now what?
The Reign of Giants DLC brought some changes into the game. For instance, when a terrible rain pours, there is a chance that frogs will come flying from the sky. After that rain there are so many of them that I couldn't count.
There is a bee hive near my base, so I guess now I have a bee sting factory. Spiders, despite the fact that they are irritated that those pesky frogs are jumping all around, hiss at them, but don't attack.
I tried bringing some pigs, but they were torn into pieces in a matter of seconds. Frogs group around all together if they see a fellow frog attacked.
I think I could bring over a Treeguard, but I'm not sure he or the frogs would attack one another.
How do I safely move the herd of frogs away from my base?
Traps work great against frogs. Manufacture a half-dozen traps, then get a few frogs to follow you into the traps. Out-run any frogs that are still following you, then go back and harvest and re-set the traps. Repeat until the frogs are all dead and you have all the frog legs you need.
Alternatively, attack a frog to get the entire army of frogs to follow you. (Fun fact: the collective noun for a group of frogs is "army.") You should be able to avoid being damaged even when using a melee weapon, but you could use a boomerang if you want to avoid all possible damage. Once they're all following you, run away. Eventually, they'll give up on following you, and the frogs will no longer be near your base. Frogs hop surprisingly fast, but they're still slower than you are and will only chase you so far.
I like to take advantage of the fact that frogs are a hostile mob. Getting frogs to attack Hounds, Koalefants, Spiders, Bees, or Pigs are all great ways to turn the amphibians into Frog Legs. Bees and Spiders are my favorites as I can harvest the now-empty nest.
I had a hard time getting them to fight Treeguards myself, but perhaps you'll have more luck.
The wiki suggests a Rock Lobster farm, but it requires the Caves, so it's for farther advanced players.