| In this paper, the character of occurrence and chemical control of Helicoverpa armigera on maize in Hexi corridor was studied in present by systematic investigation in the field. Observation by feeding in the lab and the net-room had been carried out.The results showed as follows:(1) The Helicoverpa amiyera in Hexi corridor occurrence three generations each year. In Hexi corridor,there were three generations larva whose fifth and sixth instars all occurrenced, but the sixth instar was main one. In Hexi corridor, Helicoverpa armigeva by pupa hibernated above 20cm of soil layer, and there were hardly pupa under the point. The hibernation pupa correnced from two generation. Some were from the old larvae during the last stages of the second generation. The other ones come from the third generation larva.According to the life cycle of Helicoverpa amigyra and the growth stages of maize, the second generation larva harmed most seriously on maize during corn pollination process.(2) Producing egg of imeyo of Helicoverpa amiyera was related closely to the growth stages of maize. In another word, Different growth stages of maize tempted different number of imeyo to produce egg, and as the maize grew, imego produced egg on the different part of maize. The density of population couldn't change the total selected trend to the growth process of maize, whether the density of population was higher or lower, there are much more eggs during the growth period than other stages. The imeyos liked obviously to produce eggs during corn pollination stages of maize. So they trended to birth eggs on the young tissues and the meeding organ.(3) The larva's harmed trend was that the first hatching larvae gathered mainly on corn fruit to eat silk as a result of bad pollination. After the third instar, they began to eat young fruit. After they became old, the most larvae level from above fruit, and the little from middle. The most larvae ate young fruit and silk, and their percentage in total were 56.48%and 36.80%. Only a little ones harmed leaves. The larvae from first to fourth instar harmed mainly silk, but the ones from fifth to sixth instar ate mainly young fruit.(4) There are obvious relationship between the number of larva and the rate of harmless of corn.The rate of victimize maize's fruit was 53.70%.Averayg fruit lost grain 11.7.Anout 85% fruit lost grain 6.0-20.0. Combinating practical production, it was broughtup that the controlling index was the third generation larva 47 each a hundred stubs in the field of wheat and maize, and 56 in the field of only maize. Following the number of larva each a hundred increased, the rate of victimize of maize's fruit added, too. the number of larva each a hundred and yield's rate of losing was as follow: y=-0.0618+0.0322x(n=5).(5)In the field of wheat and maize, the rate of secondly admmised losion in the different yield was 1.55%-2.17%, and controlling index was 50.09-69.35/a hundred fruits. Also, in the field of only maize, they were 1.50%-2.09% and 48.79-66.82%/a hundred fruits.(6)With field trial, the mixture preparation of methamidophos, cypermethrin and phoxim 35% EC has been screened as one of the best insecticides to control the larvae of Helicoverpa armigeva , its effectiveness after control 3d was 89.6% under 750mL/hm2. the mixture preparation of omethoate and fenvalerate 30% EC, the mixture preparation of cypermethrin and phoxim 20% EC and the mixture preparation of metribuzin and imidacloprid 4.5% ME had also high effectiveness on the larvae of Helicoverpa armigeva, their effectiveness were 87.5%, 86.3% and 83.4]frespectively. These insecticides can be the round applying chemical.(7)The results indicated that pasting over weighted dropping and spraying against the larvae of Helicoverpa armigeva. Pasting exhibited characteristics indicating high efficiency, low dosage and low cost. Therefore, the pasting measure should be spread and applied on the control of the larvae of Helicoverpa armigeva...
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