Arthropods may cause a variety of negative health effects by their stings and bites. Non-allergic reactions to stings and bites include erythematous and edematous lesions which resolve in a couple of hours, while allergic reactions may be characterized by much more serious large local phenomena and even systemic symptoms such as anaphylaxis. This chapter focuses on the medical conditions associated with arthropod bites and stings, such as those mentioned above, as well as secondary infections resulting from skin puncture. Lastly, clues to recognizing insect sting or bite reactions are presented and discussed.