Bulletin of Entomological Research (1996) 86, 423-439 423 Hymenopterous parasitoids associated with the bagworms Metisa plana and Mahasena corbetti (Lepidoptera: Psychidae) on oil palms in Peninsular Malaysia Norman H. Kamarudin Palm Oil Research Institute of Malaysia, Kuala Lumpur, Malaysia Annette K. Walker International Institute of Entomology, London, UK Mohd. Basri Wahid Palm Oil Research Institute of Malaysia, Kuala Lumpur, Malaysia John LaSalle and Andrew Polaszek International Institute of Entomology, London, UK Abstract In Peninsular Malaysia, 18 species of hymenopterous parasitoids were reared either from the oil palm bagworms, Metisa plana Walker and Mahasena corbetti Tarns, or from their parasitoids. Both Metisa plana and Mahasena corbetti share the common parasitoids Goryphus bunoh Gauld, Aulosaphes psychidivorus Muesebeck, Brachymeria carinata Joseph, Narendran & Joy, Eupelmus catoxanthae (Ferriere), Eurytoma sp., Sympiesis sp., Tetrastichus sp., and Aphanogmus thylax Polaszek & Dessart. Other parasitoids are associated with only one of the bagworm species: Paraphylax varius (Walker), Dolichogenidea metesae (Nixon), Elasmus sp., Nesolynx flavipes Ashmead, Pediobius anomalus (Gahan), Pediobius imbreus (Walker) and Teleopterus sp. from M. plana; and B. lasus (Walker), B. lugubris (Walker) and P. elasmi Ashmead from Mahasena corbetti. A key to species is included and a table summarizing the host range and distribution records are listed from the Indo- Australasian region. Introduction guineensis, in Peninsular Malaysia and several oil palm .... , ... „ , , . , , ... _ ... growing countries in South East Asia (Wood, 1982). Mod- Mehsa plana Walker and Mahasena corbetti Tarns (Lepi- ^ t( f h defoliation by these pests (commonly called doptera: Psychidae) are common pests of the oil palm, Eheis bagworms) ca y n r e d u c e the subsequent yield of oil palm by as much as 44% (Wood et «/., 1973; Wahid, 1993). They are Correspondence: A.K. Walker, International Institute of commonly known as bagworms, as the caterpillar conceals Entomology, 56 Queen's Gate, London, SW7 5JR, UK. itself inside a bag which it has spun from fragments of the