Developmental characteristics and life cycle of the lawn cutworm, Spodoptera depravata (Lepidoptera: Noctuidae)

We investigated the developmental characteristics and life cycle of the lawn cutworm, Spodoptera depravata (Lepidoptera: Noctuidae), which is one of the most important pests causing economic damage in grass production. For larval culture, we provided the zoysiagrass at $25^{\circ}C$ and $60{\pm}5%$ humidity. The durations of the developmental stages were as follows: $4.11{\pm}0.19$ days for eggs, $25.17{\pm}3.02$ for larvae, $8.80{\pm}0.28$ for pupae, and $7.57{\pm}0.95$ for adults. We grew the larvae to the 7th instar stage, unlike previous studies, in which it was assumed that the 6th instar was the final age. There was a significant positive correlation between the body length and head capsule width of each instar larvae. In terms of morphology, the eggs changed from light green immediately following oviposition to black as they developed, and the grass-fed larvae changed from light yellow immediately after hatching to green as development continued. We observed a pattern of black spots at regular intervals on the dorsal sides of the abdomens of the final instar larvae. Furthermore, we detected two notable designs on the dorsal side of the front of the head. The pupal colors changed from light brown and green immediately after pupation, to dark brown as the pupal cuticle hardened. The wingspans of the adults were similar in both sexes. However, the forewings of the males had obvious outer lines and eyespots with dark gray-brown backgrounds, whereas the corresponding features on the female forewings were less obvious. The oviposition preperiod was 2.11 days, the oviposition period was 4.2 days, the average fecundity per female was approximately 341 eggs, and the hatching rate was approximately 76.1%.