Cryptoptera dermatitis is an acute dermatitis caused by skin contact with cryptoptera venom. Cryptoptera live in damp grass, rice paddies, vegetable gardens or dark places such as under rotting wood and rocks during the daytime, and are diurnal and phototropic, flying in groups at night where there are lights, especially fluorescent lights. Every year from April to September, it breeds faster, and from July to August, it is the peak of the breeding season and also the high incidence of cryptophid dermatitis. Toxic cryptoptera is a small black ant-shaped flying insect, the body is 0.6-20px, the head black chest orange, the front abdominal position covered by black sheath wings, there are 3 pairs of feet, tail spines 2, the whole body is covered with short hairs. All segments of the body contain toxin, a strongly acidic venom, and the venom is not released when the insect crawls on the exposed skin surface at night. The venom is only released when the insect bites the skin or when the insect is beaten or crushed, causing skin damage. Overwintering as adults, the insects are inactive below 18°C and start to feed above 20°C. The rash is usually found in the morning when waking up, and is usually spotted or streaked with blisters and pustules on the exposed parts of the face, neck, chest and back and limbs. When the venomous insects start to invade the skin, there is a crawling sensation or foreign body sensation, people often scratch or turn over to crush the insects, due to the stimulation of venom, 2-4 hours later the skin appears dotted, striped redness, itching, gradually by the burning sensation, about 12 hours later the skin appears blisters, mostly transparent thin blisters, some develop into pustules, often due to scratching caused by bright red vesicles. If it invades the eyelids, it can cause eyelid redness and swelling, and the eyes cannot be opened. The disease lasts 1-2 weeks and later dries and decrusts, leaving hyperpigmentation and superficial scarring if the lesions are severe. The diagnosis can be confirmed if the worm is found. Prevention: Improve environmental hygiene, remove weeds and garbage from the vicinity of the house, and eliminate the breeding grounds of the cryptophid. Install screen doors and windows or hang mosquito nets to prevent the invasion of flying insects. Turn off the indoor lights when sleeping. If you find insects on your body, avoid grabbing or patting them directly with your hands, and trample them to death with your feet after setting them aside. Topical treatment: When the rash has no obvious vesicles or oozing, first wash the skin with soap and water, then apply topical 1% peppermint glyburide lotion or glucocorticoid cream. When there is obvious local vesicles and exudation, 1~2% alum, 5% sodium bicarbonate or 1:5000 potassium permanganate solution can be used as a wet compress. Snakebite first-aid powder or Ji Desheng snake medicine tablets mixed with water into a paste for external application also has good effect. Systemic treatment: oral antihistamine drugs, oral glucocorticoids in severe cases. If there are pustules or secondary infection occurs, anti-inflammatory treatment should be carried out.