Metisa plana Walker and Pteroma pendula Joannis are important pests of the oil palm, Elaeis guineensis Jacquin, which is the primary agricultural crop in Malaysia. Although there is a history of integrated management of the bagworms, information gaps exist with regard to their incidence, biology, dispersion and population dynamics. Such new information is needed to improve the current integrated management of these pests. Analysis of historical records of bagworm infestations over 63 955 ha of oil palm in 69 estates in Peninsular Malaysia showed M. plana and P. pendula to be the primary pests. Infestations were of single or mixed species, and ranged from nil to 7811 ha yr-1. Cumulative infestations were 18 297 ha, 4904 ha and 14 607 ha for single species of P. pendula and M. plana, and for mixed species of P. pendula and M. plana, respectively. This shows P. pendula to be the predominant species, and is attributed to its ability to survive very wet weather (>200 mm rain per month) and .....

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An attempt was made to determine optimum sampling unit of between-palm and within-palm distribution of bagworms and their interspecific association distribution in oil palm using aggregation indices or distribution models. The within-frond distribution of bagworms varied significantly within the oil palm crown. Peak bagworm density was recorded between frond numbers 9 and 19. Through polynomial regression, standardised residual and relative net precision analyses, frond number 17 was established as the representative sampling unit for experimental work, and frond numbers 10-19 should be used when a greater precision is required as in life-table construction. A lack of interspecific association suggested these sampling units to be applicable for single and mixed infestations. Evaluation of between-palm dispersion revealed that Taylor’s Power Law gave a more appropriate fit with highly significant r2 values for all categories of assessment. The bagworms were regularly dispersed in oil .....

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This article provides an accurate detail of the life history of the bagworms Pteroma pendula (P. pendula) and Metisa plana (M. plana) on oil palm. P. pendula was confirmed to possess four larval stages with no difference in the number of instars and pupal development time between the sexes. Life history of M. plana followed reported by earlier workers of 5-6 larval instars for males and 6-7 for females were used. There was, however, no difference in pupal developmental time and size. Sex ratio for both species was nevertheless 1:1 and more representative rm and _ values were obtained. The last two statistics were nevertheless superior for P. pendula and insects bred in the field. The rm for P. pendula was 0.06459 in the laboratory and 0.07327 in the field while the _ was 1.06672 in the laboratory and 1.07603 in the field; cf the rm. M. plana was 0.04783 in the laboratory and 0.06061 in the field while the _ was 1.04899 in the laboratory and 1.06248 in the field. M. plana clearly had th.....

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