If its an arthropod(spider or other insects types) in your ear is a medical concern, because it can scratch or puncture your eardrum or potentially cause an infection. Even if you succeed in removing the critter, it's wise to follow-up with a visit to the doctor, to be sure your ear canal is free from any bug bits or damage that might cause problems later.
The National Institutes of Health offers the following advice for treating insects in the ear:
DO NOT let the person put a finger in the ear, since this may make the insect sting.
Turn the person's head so that the affected side is up, and wait to see if the insect flies or crawls out.
If this doesn't work, try pouring mineral oil, olive oil, or baby oil into the ear. As you pour the oil, pull the ear lobe gently backward and upward for an adult, or backward and downward for a child. The insect should suffocate and may float out in the oil. AVOID using oil to remove any object other than an insect, since oil can cause other kinds of objects to swell.
Even if an insect appears to come out, get medical attention. Small insect parts can irritate the sensitive skin of the ear canal.