Adult specimens of two species of weevils collected in Rota sweetpotato fields by G. P. Reddy and A. Badilles were brought to me for identification. The smaller species, body length 3.3 mm, is Euscepes postfasciatus and the larger species, body length 5.9 mm, is Daealus tuberosus.
E. postfasciatus, is the West Indian sweetpotato weevil, a common pest of sweetpotato with a cosmopolitan distribution.
D. tuberosus is native to Micronesia with genus and species described from Guam by Zimmerman in 1942 1586. This is one of the few native insects of Micronesia which has become a crop pest. Pemberton 1523 characterizes Dealus sp. [note mis-spelling] as "A weevil abundant and injurious to sweet potato vines on Rota, Yap, Palau and Woleai.". More recently, in August 2003, there was a thread on PestNet about this species damaging sweetpotato on Rota 1624. Click here to see images and a summary for this species from PestNet.