The dytiscid beetle Laccophilus yoshitomiiWatanabe and Kamite, 2018 (Dytiscidae), distributed in Japan, is a small aquatic beetle that was first described in 2018. In the present study a L. yoshitomii population, collected from the type locality (Ishikawa Prefecture, Japan), was reared in the laboratory. The insects laid eggs individually into the main stems of Pogostemon sp. (Lamiaceae). The developmental period for the first, second, and third instar larvae was 2–6 (mean ± SD = 3.5 ± 0.8 days, n = 51), 3–8 (4.2 ± 0.9 days, n = 48), and 5–10 days (6.8 ± 1.3 days, n = 38), respectively; the landing to emergence and landing to escaping the pupal chamber stages lasted 8 (n = 1) and 9–14 days (11.3 ± 1.5 days, n = 13), respectively. A basic rearing model for this species is proposed.