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ThesisItem Open Access Biology and management of orchid pests(Department of Agricultural Entomology, College of Horticulture, Vellanikkara, 1998) Sajitha Kumari; KAU; Lyla, K RIn a survey conducted during 1996-97 in Kerala to study the various pests associated with orchids with reference to their biology, morphology, nature of damage and preliminary management studies on the selected pests, a total of thirteen pests were recorded. The grasshopper, Oxya chinensis (Thunberg); spiralling whitefly, Aleurodicus dispersus Russell; bihar hairy caterpillar, Diacrisia obliqua W alker; were recorded from the leaves of Spathoglottis spp. The larvae and adult of Megalurothrips distalis Karny was found infesting the buds and flowers of Dendrobium spp. and Spathoglottis spp. resulting in the destortion of buds and flowers. The tobacco catterpillar, Spodoptera litura F. was recorded from the flowers of Spathoglottis and Dendrobium spp. The ant, Monomorium indicum Forel was recorded to damage the roots of the plants. An unidentified species of Lema was recorded damaging the flowers of Spathoglottis spp. and Epidendrum spp. The grubs and adults of an unidentified curculionid was reported to cause considerable damage to Dendrobium spp. by feeding on the pseudobulbs. The banded blister beetle, Mylabris pustulata (Thunberg) was found as an occasional feeder of Spathog/ottis spp. The other pests observed during the survey were sowbug, Oniscus asellus L., land snail Ariophanta sp., black slug, Anon sp. and grey slug, Limax sp. During the studies on the morphology and biology of M distalis, the eggs were found to be bean shaped and the immature stages can be differentiated by the presence of wing pads or wing sheaths and antennal sheaths. The females inserted the eggs in the tissues of the petals and the whole life cycle ranged from 17-32 days. The adults of A. dispersus laid eggs singly covered with wax in loose whorls like fingerprints on the lower surface of the leaves. Incubation period was 5 days and the mean life cycle was found to be 45 days. During the drier conditions of the atmosphere the population of M. distalis and A. dispersus increased and there was a decline after heavy summer showers. Efficacy of insecticides against A. dispersus and insecticides and molluscide against slugs were tested. Among the insecticides tested, quinalphos , brought the highest mean mortality of the nymphs of A. dispersus (48%). In the case of slugs, 5 per cent metaldehyde bait and metaldehyde mixed carbaryl bait (2.5- 2.5%) gave the highest mean mortality of 44.44 per cent within 24 hrs of treatment. Treatment with 1 g phorate showed the highest mean mortality of 66.67 per cent after 48 hrs of treatment.