Early diagnose and treatment in spider bites of Loxosceles species is extremely important in prevention of systemic and local complications. There is not any specific laboratory test or diagnostic clue except lesion's morphology and patient anamnesis. Thus inspection in physical examination and clinical follow-up of such lesions should be remembered. Here, we present two cases of suspected insect bites, one of whom was diagnosed as necrotizing arachnidism due to spider bite.