Abstract
Last instar larva and pupa of Metadonus vuillefroyanus (Capiomont, 1868) (Curculionidae: Hyperini) are described and compared with known larvae of the other 43 hyperine taxa. The thorn-like setae located on distinct black protuberances on the larval body are characteristic features of the genus Metadonus and the subgenus Eririnomorphus of the genus Hypera. The biological singularity of this species was studied and described. The variable colouration of larvae has been confirmed in association with the variability of the host plant's colouration at the studied localities. This species' reported inability to spin cocoons has been disproven. A different type of cocoon with two layers, where the inner layer consists of proteins from Malpighian tubules while the outer layer contains soil particles, is described. This type of cocoon is unique compared with those known from other hyperines, which usually pupate on or above the ground and do not use substrate particles in building their cocoons.