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The ability of the Valencia slug Lehmannia valentiana (Férussac) to prey upon egg masses of the Oriental tea tortrix Homona magnanima Diakonoff (OTT) and the Smaller tea tortrix Adoxophyes honmai Yasuda (STT) was investigated in a rearing cage and in tea fields. In the cage, Valencia slugs prey upon an average of 6.1 to 9.3 egg masses of OTT out of placed 20 egg masses per night. In the case of STT the slugs preyed upon an average of 14.3 egg masses out of 20 egg masses per night. The total number of eggs preyed upon by a Valencia slug was equivalent to the number of eggs oviposited by one OTT female or two STT females. In tea fields, Valencia slugs preyed upon the egg masses of OTT that were both experimentally attached to tea leaves and oviposited on the leaves. The number of egg masses preyed upon by slugs differed among the tea fields, and it tended to be related to the number of slugs captured in traps. Copper sprayed on the egg masses of tea tortrix had no influence on predation by Valencia slugs, however, spraying of organophosphorus and carbamate insecticides did have an influence on slugs predation.

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