The hardening of the protein component of insect cuticle has been shown to be due to the tanning action of an agent produced by oxidation of a phenolic substance forming sclerotin.  In the analogous hardening of the cockroach ootheca, the phenolic substance concerned is 3:4-dihydroxybenzoic acid (protocatechuic acid).
Acetosyringone is produced by the male leaffooted bug (Leptoglossus phyllopus) and used in its communication system. Guaiacol is produced in the gut of Desert locusts, Schistocerca gregaria, by the breakdown of plant material. This process is undertaken by the gut bacterium Pantoea agglomerans. Guaiacol is one of the main components of the pheromones that cause locust swarming. Orcinol has been detected in the "toxic glue" of the ant species Camponotus saundersi.  Rhynchophorus ferrugineus (red palm weevil) use 2-methoxy-4-vinylphenol for chemical signaling (pheromones). Other simple and complex phenols can be found in eusocial ants (such as Crematogaster) as components of venom.