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can be prominent features of the inflammatory reaction, a common conundrum in the ED is determining whether an insect bite has become infected In our experience, cellulitis, indicative of infection, is tender and tends to be firmer than a simple inflammatory reaction Unfortunately, no specific treatment exists for insect bites Antihistamines, calamine lotion, or topical steroids have a limited or temporary effect Prevention through the prophylactic use of insect repellents and protective clothing offers the best solution Elimination of the biting insects by treatment of the homes with insecticides or treatment of the infested animals is important For additional information about insect bites, see Chapter 67 Rash: Vesiculobullous Tick Bites Tick bites usually cause only local reactions Erythema migrans is the characteristic rash of Lyme disease and looks like large bull’s eye; the rash generally appears to 10 days post tick exposure but the range is to 30 days and is not always seen Rarely, tick bites are associated with significant systemic illness, including Rocky Mountain spotted fever (RMSF), tick paralysis, and Lyme meningitis When ticks are removed, it is important not to leave fragments of the mouthparts in the skin or to introduce body fluids containing infectious organisms Various methods have been recommended for removal of ticks from the skin The safest method is to use a blunt-curved forceps, tweezers, or fingers protected by rubber gloves The tick is grasped close to the skin surface and pulled upward with a steady even force The tick should not be squeezed, crushed, or punctured If mouthparts are left in the skin, they should be removed Spider Bites Loxosceles reclusa , or the brown recluse spider ( Fig 88.4 ), found most commonly in the south central United States (from southeastern Nebraska through Texas, east through southern Ohio and Georgia), is responsible for most skin reactions caused by the bite of a spider This spider is small, the body being only to 10 mm long, and bears a violin-shaped band over the dorsal cephalothorax The venom contains necrotizing, hemolytic, and spreading factors The initial symptoms include mild stinging and/or pruritus A hemorrhagic blister then appears, which can develop into a gangrenous eschar Severe bites can cause a generalized erythematous macular eruption, nausea, vomiting, chills, malaise, muscle aches, and hemolysis Treatment includes tetanus prophylaxis and surgical removal of the necrotic area to prevent spread of the toxin