The active ingredient in Jungle Formula Roll-On Max is typically a substance like DEET (N,N-diethyl-meta-toluamide), which is one of the most effective and widely used insect repellents. DEET works by masking the scent of carbon dioxide and lactic acid, which are chemicals emitted by humans and attract mosquitoes. By doing so, it makes it harder for mosquitoes to detect and bite you.