What is the primary active irritant chemical in the hemolymph causing Paederus dermatitis?

Pederin

The inflammatory condition known as paederus dermatitis is initiated by a chemical agent released from the beetle's internal fluid, known as hemolymph. The specific, highly potent irritant responsible for the severe chemical injury is pederin. This compound is renowned for its toxicity, capable of causing intense irritation and blistering even upon contact with surfaces where the dead beetle or its remnants have rested. Crucially, the text specifies that pederin is actively produced by the beetle itself, rather than being acquired or sequestered from its diet. This distinguishes the chemical injury from mechanical injury associated with a true bite. The mechanism involves the toxin being transferred to the skin, often when the beetle is accidentally crushed, initiating the subsequent pathological reaction.