Euproctis similis dermatitis is a dermatitis caused by the poisonous hairs of euproctis similis.


The pathogen is euproctis similis, also known as yellow-tail moth caterpillar.

Yellow-tail moth caterpillar has numerous poisonous hairs. The center of the poisonous hairs is a hollow tube with venom. When the deciduous poisonous hairs in the wind are adhered to the human body, humans may be diseased.

Signs and Symptoms

After the poisonous hairs prick the human skin, local severe pruritus and pain occur within few minutes to hours. Subsequently, there are pinhead sized to pea sized, edematous, light red macules, developing into scattered, pea sized, round or irregular, light red to bright red maculopapular rash, papulovesicular rash, or wheals in few hours. There is obvious edema. There is a piercing point in the center. There may be pea sized, edematous, red papules in few patients, with pinhead sized vesicles in the center, developing into erosion after scratches or abrasion, followed by encrustation and decrustation.

The predilection sites are mainly the exposed areas such as the neck, chest, back, shoulders, and forearms.

Poisonous hairs in the eyes can cause conjunctivitis and keratitis. The toxicity of the hairs can maintain for 2 years. Therefore, ingestion of water containing poisonous hairs or inhalation of poisonous hairs can cause oral or upper respiratory tract infections, and patients present with severe pruritus, particularly before going to bed at night.

The disease can persist for about 1 week, up to 2 weeks, and can heal spontaneously. If there are continuous stimulations or scratches, the disease may last for 2 - 3 weeks.


On the basis of clinical manifestations, the disease can be diagnosed.


Topical calamine lotion can be used, and oral antihistamines may be appropriate if there is severe pruritus after external treatment.