A novel chemical subclass of toxin, [1‐(3‐diazenylphenyl)ethanol]iron, was identified among the compounds present in the web of the spider Nephila clavipes. This type of compound is not common among natural products, mainly in spider‐venom toxins; it was shown to be a potent paralytic and/or lethal toxin applied by the spider over its web to ensure prey capture only by topical application. The structure was elucidated by means of ESI mass spectrometry, 1H‐NMR spectroscopy, high‐resolution (HR) mass spectrometry, and ICP spectrometry. The structure of [1‐(3‐diazenylphenyl)ethanol]iron and the study of its insecticidal action may be used as a starting point for the development of new drugs for pest control in agriculture.