A sieving method for separating insect pupae is described. The method may include causing an actuation system of a sieving apparatus to cycle between a first elevation and a second elevation to cyclically submerge a sieve surface of a sieving device in a liquid held within a basin so as to separate a population of insect pupae present in the sieving device with respect to size. The method may also include causing actuation of one or more valves to drain the liquid from the basin in order to retrieve a first part of the population of insect pupae.