Wolf lairs will be bigger on World 1 as they are based on the average rank but there is still a random chance of getting a small lair. Dellwyndria already mentioned scouting and this is always the best thing to do. Then you know how many wolves you are up against.
The wolf AI was improved a while ago and this means that they are harder to kill. Below is some stats that fellow moderator Dru. worked out.
Scout the wolf lair then:
The above should give you an idea of what army you need to take out the lairs.Armed peasants without upgrade (conscription/hit points) will be about 8 peasants to 1 wolf but it also depends on where they are placed since melee run right past them. If you use archers as well, then less peasants are needed.
When scouting send all 8 scouts if you can. The more you send the better chance of gaining a successful report.