Treeguards are Boss Monsters that can occasionally transform from Evergreens when a nearby Evergreen is chopped down. They are initially hostile towards the wood-cutter, assuming that is how they were spawned, have very high health and damage, and are capable of killing most unarmored characters in three strikes.

Treeguards do not normally spawn before Day 3, after which each Evergreen at any stage fallen has a 1.33% chance of spawning one from a nearby tree. After Day 30, up to two Treeguards may spawn at once, with up to three spawning after Day 80 given enough Evergreens nearby. They can spawn from any size Evergreen tree, besides Evergreen saplings (from recently planted Pine Cones) burned and dead Evergreens or Lumpy Evergreens.

Treeguards have a great deal of health but are slow. Killing the monster by dodging its attack and then running in to strike 3-4 times before dodging again is an effective way to wear it down, although this will drain considerable Sanity. This method works especially well with Woodie's Beaver form.

Alternatively, they can be put to sleep using the Pan Flute or Sleep Darts, or frozen with the Ice Staff.

Leading a Treeguard to other hostile creatures or vice versa is another effective way to kill it. Pigs will attack them on sight, and multiple Pigs can easily disorient a Treeguard by hit and run tactics. A good-sized herd of Beefalo in heat can make short work of a Treeguard, and due to its ability to be pacified, the Treeguard can be placed close to a herd and effectively farmed every mating season (also yielding Meat and Beefalo Horn drops). They can also be tricked into fighting Deerclopses, Hounds, and Tentacles. Another possible way to kill a Treeguard is to pacify it by planting pine cones and light surrounding things on fire; it will catch fire but won't wake up, though this method causes the Living Logs it drops to burn into ashes, and Living Logs are surprisingly useful.

A good way of killing Treeguards with Woodie is to gnaw trees to try and spawn one in Woodie's Werebeaver form. The Werebeaver needs to eat a lot of plant matter to keep his Log Meter up, so it's likely Treeguards will eventually spawn.

If you set a nearby tree alight and the Treeguard walks next to it, He will light up and take periodical damage. If killed by fire, he will not drop the usual loot but will leave some ash and cooked monster meat.

Having trouble while trying to summon a Treeguard is quite normal. A way to speed up this process is to have some befriended Pigs help chop trees. They will continue to chop trees until the player runs a distance from the trees. If the Pigs spawn Treeguards, the Treeguards will attack the Pigs instead of the player. Another way is to burn a large area of trees, then chopping the burnt trees down. Since burnt trees are counted, it is possible to get one by chopping a bunch of burnt then going to a regular tree.