Objective To understand the population density, habitat, area distribution, and seasonal patterns of cockroaches in Zhejiang province from 2020 to 2024, and provide evidence for the development of cockroach control measures.

Methods From 2020 to 2024, surveillance points were set up in all counties (districts) in 11 prefectures in Zhejiang, and cockroach density was investigated by using the sticky trap every two months. The data were processed and analyzed by using Excel 2021 and software R4.0.2, the maps were generated by using software ArcGIS 10.8. Kruskal-Wallis H test was conducted for statistical analysis on the cockroach density across different habitats, areas, and years. For indicators with significant differences, the post-hoc pairwise comparisons were conducted to further analyze the differences between groups.

Results From 2020 to 2024, a total of 391746 rooms were investigated in Zhejiang, and cockroaches were found in 19455 rooms, indicating a cockroach infestation rate of 4.97%. A total of 381359 cockroach sticky traps were placed, and 172084 cockroaches were captured, the cockroach density was 0.45 cockroachesper trap. Blattella germanica was the predominant species, accounting for 97.27% of the total captures. In different areas, the highest cockroach density was found in Taizhou (1.26 cockroaches per trap), followed by Jinhua (0.74 cockroachesper trap), Lishui (0.67cockroaches per trap) and Hangzhou (0.63 cockroachesper trap), and the lowest cockroach density was found in Ningbo (0.04 cockroachesper trap) (H=210.176, P＜0.001). The highest cockroach infestation rates were found in Taizhou (8.85%), followed by Wenzhou (8.16%), while the lowest cockroach infestation was found in Ningbo (1.35%) (H=177.654, P＜0.001). In terms of cockroach habitat, The highest cockroach density was found in farm produce markets, followed by supermarkets/catering places, hotels/residential areas and hospitals (H = 178.857, P < 0.001). The highesr infestation rate of cockroaches was also foundt in farm produce markets, followed by catering places/supermarkets, and residential areas/hotels/hospitals (H = 177.975, P < 0.001). The seasonal pattern of cockroach density showed a bimodal peak distribution, the density began to increase in January, had the sub-peak around May, and peaked in November.

Conclusion In Zhejiang, B. germanica is the predominant species, and the farm produce market is the cockroach habitat with the highest cockroach density. The cockroach density shows a bimodal peak distribution. Effective control measures should be taken targeting key habitats, predominant species, and density peakperiods of cockroaches