Mosquito bags on the buttocks is considered to be papular urticaria, papular urticaria occurs in infants and children, in a family there may be several children at the same time onset, spring and fall season occurs more. Papular urticaria occurs on the trunk, limb extensors, clustered or scattered, for the mung bean to peanut-sized, slightly fusiform red, wind-breakout-like damage, the top of the severe blisters, skin color, reddish or brownish, new and old rashes can be present at the same time. In young children, the redness, swelling and blisters are prominent, accompanied by intense itching and even sleep disruption, and scratching can cause bacterial infections. Treatment can be topical glycerite lotion 3-5 times/day, if the itching is obvious, can also apply corticosteroid cream, secondary infection patients should be topical antibiotic ointment such as mupirocin ointment, itching is severe can be considered oral antihistamine medication, such as loratadine, ibogaine, and so on.