Life history of the white grub Dasylepida sp. (Coleoptera: Scarabaeidae), a new and severe pest on sugarcane on the Miyako Islands, Okinawa.

The life history of the white grub Dasylepida sp. was surveyed in a sugarcane field in Miyako Is., Okinawa, Japan. Adult flights were observed from early February to mid-March in 2001. Adults commenced flight just after sunset (at around 18:30) and mated. Sampling from the pots placed in the field on 19 April yielded 41.8% eggs and 58.2% first stadium larvae. Larvae sampled on 20 June, 2000 were found to consist of 33.3% and 66.7% of the first and second stadium larvae, respectively. On 22 August, 87.5% of larvae were second stadium and the remainder (12.5%) were third stadium larvae. The proportion of third stadium larvae increased and attained 100% by 30 November. In an excavation survey on 26 November, 2001, 11 adults (three females and eight males) and five pupae were found in the soil at a depth of around 45 cm. Pupae were found in the tunnel cavities. We believe that adults remain in the tunnels until the next February. In the rearing experiments at 25degreesC in the laboratory, the egg period was 23.6 d and the larval periods of the first, second and third stadia were 80.9, 91.8 and 335.8 d, respectively. These facts indicated that Dasylepida sp. has a two-year life cycle.