Salicylaldehyde be prepared from the corresponding phenol by the Duff reaction, or by treatment with paraformaldehyde in the presence of magnesium chloride and a base. Salicylaldehyde was identified as a characteristic aroma component of buckwheat. It is also one of the components of castoreum, the exudate from the castor sacs of the mature North American beaver ("Castor canadensis") and the European beaver ("Castor fiber"), used in perfumery. Furthermore, salicylaldehyde occurs in the larval defensive secretions of several leaf beetle species that belong the subtribe Chrysomelina. An example for a leaf beetle species that produces salicylaldehyde is the red poplar leaf beetle
Castor and Pollux represented in the Circus Maximus by the use of eggs as lap counters. In translations of comedies by Plautus, women generally swear by Castor, and men by Pollux; this is exemplified by the slave-woman character Staphyla in "A Pot of Gold" (act i, ll.67–71) where she swears by Castor in line 67, then the negative prefix in line 71 denotes a refutation against swearing by Pollux. The Etruscans venerated the twins as "Kastur" and "Pultuce", collectively the "tinas cliniiaras", "sons of Tinia," the Etruscan counterpart of Zeus. They were often portrayed on Etruscan mirrors. As was the fashion in Greece,