Description of the developmental stages of Sosylus spp. (Coleoptera: Colydiidae) from New Guinea, parasites and predators of ambrosia beetles (Coleoptera: Platypodidae)

A description is given of some of the developmental stages of Sosylus vicinus (Grouv.), S. silius Hinton and S. reflexus Pope from Papua New Guinea. At least three instars are recognised in all species, and the first or primary instar is of the triungulin type. A triungulin is also reported as the primary instar of another colydiid, Asosylus rhysodoides (Pasc.). This is the first time triungulins have been found in the coleopterous family Colydiidae. Differences in the triungulin of the three species of Sosylus are recognised, based on the form and arrangement of segmental spines. The structure of the different instars with regard to their habits on the host is discussed, and a brief comparison is made with larvae of Meloidae and Rhipiphoridae, the only two other families of Coleoptera with triungulin first-instar larvae.