,  , This study was conducted to investigate food preference and developmental characteristics of the gray field slug, Deroceras reticulatum Muller (Stylommatophora: Limacidae) using various foods. The food preference of D. reticulatum was most highest on Chinese cabbage (Brassica campestris L.), followed on cucumber (Cucumis sativus L.), and significantly low on beet (Beta vulgaris var. Ruba), kale(Brassica oleracea L. var. acephala D.C), carrot (Daucus carota L.) and Chinese cabbage (Brassica campestris L.) which were not different significantly. The total number of eggs laid by D. reticulatum was the highest (n = 109.6) on cucumber and the lowest (n = 10.1) on leaf perilla (Perilla frutescens var. japonica Hara). Hatchability was the highest (92.4%) on cucumber and the lowest (62.5%) on leaf perilla. The egg developmental period was not significantly different from 12 days to 13 days among host plants. Juvenile period and adult longevity ranged from 75 days to 111 days and 66 days to 187 days, respectively. Thereby, life span from egg to adult longevity of D. reticulatum was the longest on cucumber with 273 days and the shortest on 190 days on leaf perilla.

The egg size and weight of the gray field slug, Deroceras reticulatum Müller, was 1.91×2.19 ㎜ and 3.3 ㎎ at 24℃, respectively. Its weight increased from newly laid eggs to adults for 17 weeks at four temperature regimes and was heaviest at 20℃, followed by 24, 16 and 28℃. Likewise, hatching rate of the egg batches was highest with 95% at 20℃, followed by 24, 16 and 28℃ with significant differences. The number of eggs in the batches was increased with 20 at 20℃ while it was only 10 at 28℃. The average accumulated egg-laying days was longest with 15 days at 20℃ while shortest with 9 days at 24℃. The range of egg-laying period was shortest with 84-134 days at 16℃ and longest at 20℃. Thus, the total number of eggs laid by adult D. reticulatum was highest with 217 at 20℃ and lowest with 105 at 16℃. The egg period was 12-19 days while the juvenile period and adult longevity were 51-68 days and 85-134 days, respectively. The life span of D. reticulatum from egg to adult was longest with 216 days at 20℃, followed by 193 days at 24℃, 170 days at 16℃ and 151 days at 28℃. Accordingly, the most favorable temperature for the oviposition, development and longevity of D. reticulatum is 20℃.