A 4-year-old boy presented with erythematous vesicular linear streaks over left cheek and erythematous papular eruption of lobule of left ear since 3 days (Fig. 1). It was of sudden onset noticed first in the morning with burning sensation over lesions. Except for that, rest of the physical examination was within normal limits. He did not remember any contact with insects. Oral antihistamines and topical antibiotics steroid cream was advised on an out-patient basis.

Fig. 1 Paederus dermatitis on left check and lobule of ear.

Pederus dermatitis (Bhiter beetle dermatitis or insect-bite reaction) is a contact irritant dermatitis. It is characterized by sudden onset of erythematobullous lesions on exposed areas of the body caused by accidental contact of a beetle of genus Paederus. It contains a toxin paederin present in beetle coelomic fluid. Brushing or crushing of the beetle causes contact of paederin with skin resulting in peculiar skin lesions. Principal differential diagnosis includes phytophoto-dermatitis, thermal and chemical burns. If patient presents early, washing with soap and water is helpful. Treatment includes soothing agents, oral antihistamines and topical antibiotics-steroid cream for local application.