| This paper used the methods of investigating in the field and cultivating in the lab, we found that Melolontha hippocastan mongolica Menetries developed five years a generation in ZheDuo mountain, KangDing,SiChuan province.The adult in the winter began unearthing at the end of April,peaked between mid-May and early June.The adult of Melolontha hippocastan mongolica Menetries fed on leaves of spruces and kangding polars,mated several times before spawning, (115.6±24.4) (n=10) each time in averge.The female adult made a round chamber about 5cm to 10cm under the ground when the eggs riped in June, peaked in August about 81.9eggs/M~2 ,there were (33.7±7.0) (n=10) eggs per chamber in averge, the rhythm of mating is in the form of "M",there are two peaks in noon and night. The first larvas were found in July, peaked in September. The larvas went into more than 20cm in the earth in winter after November. In 2008,the main soil insects were larval and adult oblitas in March , 5.0/ M~2 and 7.5/ M~2 respectively, larvas in September were 86.9/ M~2. The natural enemies of Melolontha hippocastan mongolica Menetries were Beauveria brongniartii Petch,carabidaes, ants, Upupa epops saturates etc. Beauveria brongniartii Petch and carabidaes were the main enemies, the natural infection rate in the field was 3.6% in March and 13.5% in April,there was less in other months, there were 7.6/M~2 of carabidaes in November.The process that Beauveria brongniartii Petch developed in the vivo of second age of Melolontha hippocastan mongolica Menetries larva was observed, there were five stages with the methods of hemolymph and paraffin section.The mortality rate that Beauveria brongniartii Petch to the first age Melolontha hippocastan mongolica Menetries larva was over 95% in the lab,the least infection rate was 80%, which means there was strong virulence to the first age larva.But there is not much virulence to the third age larva,eggs and adult Melolontha hippocastan mongolica Menetries.In the experiment in the field,the infection rate of method fourth was notable compared to CK in July,2008,but the infection rates of all methods were not notable compared to CK in September,2008.As to different methods of applying Beauveria brongniartii Petch to the Melolontha hippocastan mongolica Menetries larva in the field, the application volume is 2kg / 666. 7m~2,each test aera was 200m~2,repeat three times of each,results were all notable compared to CK,the results of sprayed methods were best,scattered were better compared to ditched one.The control of Melolontha hippocastan mongolica Menetries,used the method of biological control on the base of data invesgated from the field.Use Beauveria brongniartii Petch to control the larval oblita(Melolontha hippocastan mongolica Menetries in main).Sprayed Beauveria brongniartii Petch on the ground, permeated them by water,CK with no Beauveria brongniartii Petch,there were 7 methods, repeat three times of each, each test aera was 200m~2. There were six methods to the larva(Melolontha hippocastan mongolica Menetries in main)in all,the results were that: methods 1 and 6 had the most decline rate and control effect;the density of larva(Melolontha hippocastan mongolica Menetries in main) of method 1 after applying was least;the decline volume of larva(Melolontha hippocastan mongolica Menetries in main) of method 6 was most,the growth rate and density of carabidae was most.From the long-term effct,we should use the method 6 in practice.Choosed a test area of 666. 7m~2,sprayed 8000.00ml Beauveria brongniartii Petch on the ground, permeated them by water.Inspect the infected insects in two months. The hosts of Beauveria brongniartii Petch are soil pests and natural enemies such as oblitas, agrotises, carabidaes, parasitic flies,aphids etc.Killed the adults of Melolontha hippocastan mongolica Menetries by trapping is also a effective method.
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