What can I do if I have over 100 spider bites from spiders in my apartment?

First, tell your landlord, if you haven't already: the landlord has to take reasonable steps (e.g. call and schedule an exteriminator, including multiple visits, if necessary) to address pest infestations.

Second, if you had already told your landlord and he/she did not take any reasonable action to deal with the situation, then 1) you *might* be able to treat the lease as terminated due to the landlord's breach of the "implied warranty of habitability" (the obligation that he provide habitable and safe premises); 2) you may be able to withhold rent until the problem is addressed; and/or 3) you may be able to sue the landlord for your out-of-pocket medical costs & lost wages (if any) from the bites.  The key is you first must have made the landlord aware of the situation, then he/she must have had some chance or opportunity to address it, since the landlord is not liable unless at fault, and fault depends on knowing there was a problem and having a chance to fix it, but still failing to do so. If you did previously let your landlord know, but the landlord did nothing, and if you want to explore your various legal options, consult with a landlord-tenant attorney.