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S4 Zho/l Darong, He Kanglai and Song Yanyinglow release level (7,500 to 15,000 waspsfha) in the earlier stage of the generation. can get as highparasitism as the normal level release (150,000 waspsfha). A great progress in mass production ofartificial host eggs of T spp has been achieved. A semi-mechanized production line for artificial eggcardsof these tiny wasps is capable of producing about 800 sheets per hour. The daily production of Tdendrolill1i is 30 millions and for T chi/ois is 18 millions. The total cropping area released with Tspp produced from artificial eggs are estimated at 933 has annually. An average area released with Tdendrolimi, produced with natural host eggs for controlling the ACB, reached 2 million ha from 1974to 1989 in Liaoning Province. It was as high as 81.:'3% of the parasitism obtained in controlling theACB by releasing artificially produced T dendrolimi (Shen et a!. 19 1).Many parasitic insects have been found to attack the CB larvae, which are consumed andkilled by these species. Investigations have found that MClcrocenrr/ls linear is abundant in theSha dong Province. The natural parasitism can be as high as 40-50 t. on the overwinteringgeneration, which is an important factor in reducing the population of ACB (Fen et a!. 1987). Thisspecies attach an average of about 20-30% of ACB overwintering larvae in most of the northeasternmaize region (Cui et al 1983). But in Hebei Province, it was found that about 30-40% of the ACBlarvae was affected by the tachinid t1y, Lvdella grisescens (Wang 1982).B. bassiana is very widely used to control ACB in the northeastern region. The formulatedcommercial insecticide was applied to piled, infested corn stalks, where it kills the overwinteringlarvae. By treating stalks and stubble piled near villages, damages to corn in the following seasoncan be reduced by more than 8610 (Guo & Wang (982). New processing technology andformulations for B. bassiana have been developed. The annual area applied with th se microbialpesticides is about 660,000 ha (Zhou et al J992). This fungus can be cultured in the corn whorl withsmall amount of media, abuut 6 t 8 times increase have been obtained. the damage to corn can bedecreased by 86.2% (Xu et al 1987). Bacill/ls thuringiensis is another important microbial pesticideswidely Llsed in China. It is usually applied by formulated granules, the damage could be reduced by80% (Zhou & He 1995). The production of B. thuringiensis is up to 1500 tons in 19 O. A veryeffective species of microsporidian, Nosema fimwculis Wen was found to infest ACB in China lWen1986. Wen et a!. 1986), but the infestation varied, depending on the regions. The heavy infectionswere found in the areas with univotine ACB. The infection could be enhanced by artificialinfestation. The most efficient transmission occurred at the silk stage of corn development (Wen1985). Some studie' show that about 90% of ACB larvae were killed by 6 days after applying thenematode. Steinemema feltiae agriotis, in the whorl of corn (He et al. 1991 a, 1991 b, 1992).2.5 Chemical controlNumerous insecticides such as nBC, methyl and ethyl parathion, Phoxim, Carbofuran, andSumicidin and variant application methods have been tested and used against A B on maize.Although chemical control were limited because of environmental pollution, to apply O,5lJo parathiongranules into the whorl at the late whorl stage of corn development are still the most effective andpracticable way to control ACB infestations. Furthermore, a commercial granule of 3% parathion asa high concentration-low dosage preparation has been proved to be as effective as the former (Zhanget a!. 1980, Sun et a!. 1988). A specially designed applicator was developed coincidentally. It hasbeen adopted in large scale extended in the Yellow River and Huai River vaHey areas.It was found that the population of ACB had developed resistance to BHC and can quicklydevelop resistance to the pyrethroids, such as Sumicidin, under laboratory conditions and Furnadanas well. However, the ACB did not develop resistance to Methyl Parathion. This show that theorganothosphates are idealistic insecticides for substituting the chlorinated hydrocarbons. Moreover,a synergistic effect of about 10% was obtained when Carbaryl were used together with B. bassiana.As for adults control, a special control measure with DDVP releasing bags hanged in the fieldfor controlling the first generation moths had been developed, the number of egg masses per 100plants were decreased by 86% (Xin et a!. 1986). Similar method with DDVP+lsofenphosmethyl