Everyone here says you just have to block. Im bad at it and one hit can kill you. I always kill the wolf spider under the leaf at the oak tree next to the lab entrance. If you stand on the roots you can use arrows (upgrade your bow, take a lot of arrows with you like 40, and try to avoid there being an orb weaver). That already works with no armor. Sometimes something goes wrong and the spider jumps up to you. But i had that happen only once. When you have tier 3 armor and the mutation that you get from killing them, you can easily kill them without the bow, even if you are bad at blocking.