TL;DR: Both species of bagworm should be considered as potential pests of guayule plantations in areas of southern Africa.
Abstract: Larvae of the bagworm Eumeta hardenbergi (Bourgogne) (Lepidoptera: Psychidae) are reported for the first time to feed on the leaves and bark of guayule (Parthenium argentatum Gray) plants which were being examined as a potential source of natural rubber in Pietermaritzburg, Natal, South Africa. Plant damage due to the removal of stem shoots for bag construction by a light infestation of larvae was assessed. Subsequent losses in rubber yield were estimated to be c. 100 kg ha−1. An unidentified bagworm was also found feeding on guayule leaves. Both species of bagworm should be considered as potential pests of guayule plantations in areas of southern Africa.