【Abstract】　Objective　To grasp the dynamic change of the population distribution and seasonal fluctuation of cockroach in Dalian. Methods　The baits and traps method was used in the surveillance. Results　There were 3 species of cockroaches, and Blattella germanica was the dominant species, accounting for 96.89%. Periplaneta japonica and P.fuliginosa accounted for 3.02% and 0.09% respectively. The activity peak of the cockroach was from July to  October. The order of cockroach distributed in different trade was farm produce trade market, residential area, restaurant, hotel and hospital. Conclusion　B.germanica was the dominant species in Dalian, suggesting that it should put the emphasis on the control of it in the future.

Objective To analyze the case feature and epidemic tendency of Epidemic Encephalitis B(EEB) in Dalian during 1951-2002 for understanding the epidemic regularity and formulating a countermeasure to control it.Methods Epidemiology and statistics.Results There had been 7 902 patients with EEB and 5 prevalent peaks in whole city during 1951-2002.The annual average incidence rate was 3.49/10⁵.The cases had characteristic of disperse and focus.There were the major areas of patients in Zhuanghe,Pulandian and Wafangdian,according for 68.43% of total cases.There were greatest numbers of cases in August,September,according for 94.01% of total cases.The chief vehicle of disseminate of EEB was Culex tritaeniorhynchus.Culex pipiens pallens was dominant mosquito in Dalian recently years.Conclusion By inoculating the inactived vaccine and clearing the heavy infestation of mosquitoes,the spread of disease can be controlled effectively.