Biological control of Liriomyza trifolii (Burgess) using Diglyphus isaea (Walker) has been evaluated in tomato greenhouse, for three seasonal culture types: spring type (March-July), summer type (June-October) and autumn type (July-December). For spring type, totally 5.8 individuals/㎡ of D. isaea has been released at six times from late April, when the density of L. trifolii was about 1.0 individuals/plant. Corrected mortality of Liriomyza trifolii caused by parasitoids was 97.6% at early July, and the proportion of D. isaea was 88.9% of all parasitoids collected in the greenhouse. In the case of summer type, totally 1.8 individuals/㎡ of D. isaea has been released at five times from early July, when the density of L. trifolii was about 0.4 individuals/plant. Corrected mortality of L. trifolii caused by parasitoids was 84.4% during the whole season, but the proportion of D. isaea was very low (only 13.8%). Immigrating parasitoids such as Chrysocharis penthus were synchronized to control the leafminer in the greenhouse. For autumn type, totally 2.7 individuals/㎡ of D. isaea has been released at four times from mid September, when the density of L. trifolii was about 0.7 individuals/plant. Corrected mortality of L. trifolii caused by parasitoids was 85.7% at mid December, and the proportion of the D. isaea was 83.4%.

Experiments have been performed to investigate biological characteristics of Diglyphus isaea (Walker), an ectoparasite of Liriomyza trifolii (Burgess). At 25℃, development time of D. isaea was estimated as 1.3 days for eggs, 4.5 days for larvae and 6.3 days for pupae. Adult longevity was 25.1 days, and a female adult could lay 305.3 eggs throughout its lifetime. Number of L. trifolii parasitized or killed by the wasp was 962.2 individuals/adult. Most of all parasitized or killed larvae were identified as third instar. With 20% honeyed water as food source, half of the adults could survive 180 days at 5℃, 150 days at 10℃, and 90 days at 15℃. After storing at 10℃ with absolute honey for 30 days, 70 days and 140 days, a female adult in room temperature laid eggs 190.8 individuals, 104.0 individuals and 89.4 individuals, respectively.