Larval behavior of Dinoptera minuta (Gebler) (Coleoptera: Cerambycidae) was observed in natural and experimental situations. In dead twigs of Cornus controversa, the larvae were found only under the rotten, fragile bark, and were observed to subsist on inner phloem, whereas xylem portions were never eaten. Mature larvae crept under the bark with their dorsum facing the xylem side. Meanwhile, as the outer phloem was broken, mature larvae left the dead twig and burrowed into the soil beneath. In the laboratory, movement of the larvae from the twigs to the soil took place from late August to late December. Most of the mature larvae transferred to test tubes filled with soil were observed to stay at certain positions in the soil at an average depth of 4.3 cm. A comparison of digestive tracts of an immature feeding larva and a mature moving larva revealed little change of total tract length, marked atrophy of the midgut of the latter, little change of hindgut, and a color change from ocherous to clear white, suggesting mature larvae in the soil ingest water but do not feed. Movement from twig to soil in autumn, followed by formation of the pupal chamber of an individual in early January, suggests that the species is univoltine in the lowland of Honshu, Japan.