Previous studies show that pupating in soil is essential for Heortia vitessoides Moore (Lepidoptera: Crambidae) to complete its life cycle. However, little is known of the process. In the present study, we observed soil-burrowing and pupal-chamber construction by prepupae of H. vitessoides in 0.5-cm-wide acrylic plate interlayers. In bioassays, we also investigated pupation behaviors and pupal physiology and morphology in response to soil moistures of 5%, 25%, 45%, and 65% water saturation. Prepupae burrowed significantly deeper in soils with higher levels of soil moisture and constructed larger pupal chambers at 65% water saturation. H. vitessoides pupae also had significantly greater percentage biomass loss and lower body water content when the soil moistures were lower. Interestingly, pupae in 5% saturated soil were smaller and showed a significantly higher surface-to-volume ratio than at other soil moisture levels, which might pose challenges in water conservation.