Several archaic features of interpreting the surrounding world are still present in Udmurt folk culture. Calendar-related customs and feasts still preserve the oldest elements at all levels of rituals: in activities, artefacts, verbal and acoustic fields, etc. The dismissal of pests and caterpillars, and their wedding rituals, are deeply rooted in calendar customs. The thorough study of the codes of these rituals would help to determine the semantics of rituals, ascertaining the synchronic-diachronic aspects of the calendar, and provide an integral imagination with regard to the mythopoetic foundations of popular worldview. Relying on the analysis of the specificity of Udmurt calendar feasts and customs, it becomes obvious that the tradition of warding off vermin takes place in different seasons and is an inseparable part of the calendar cycle. Having analysed the specificity of Udmurt calendar feasts and customs, the rituals associated with the dismissal of insects is intrinsically polyfunctional, whereas the most archaic feature therein is the idea of conjuring the rain.