Head lice are transmitted by head to head contact. Optimal therapy includes malathion lotion 0.5% repeated in one week left on for 30 minutes to 8 hours. Spinosad topical suspension 0.9% repeated in one week left on for 10 minutes is another option. Scabies is transmitted mainly by direct contact but also via heavily infested fomites due to crusted scabies. Permethrin 5% cream to the body repeated in four days is often sufficient; however, scalp treatment with malathion lotion 0.5% is helpful in crusted scabies and in infested children. Oral ivermectin 200 mcg/kg is another option, repeated in four days. For scabies more than lice, fomites should be placed in a drier at 60 °C for 10 minutes to kill the arthropods. Treatment of close contacts in both cases will control outbreaks and repeated infestations. Both have been associated with methicillin-resistant Staphylococcus aureus infection. Bed bugs are a common cause for papular urticaria. Identification of the insect in the mattress or bedding confirms the diagnosis. Prevention involves encasing the mattress in a sealed plastic cover and extermination. Delusions of parasitosis is a diagnosis of exclusion that is best treated with an antipsychotic.