Week 25

Week 25 (June 17-23) Winnipeg Mosquito Summary - 2024

Trap counts are relatively high compared to previous weeks and recent years. To protect yourself from mosquitoes, reduce time spent outdoors from dusk until dawn, wear long, loose-fitting light coloured clothing and apply insect repellent containing 30% DEET.

Week 25 Summary

The City of Winnipeg trapped on all days this week, deploying 37 traps per day for a total of 259 mosquito trapping events.

Compared to the average trap count last week (average trap count: 20.19) there has been a 62.01% increase in mosquito activity this week (average trap count: 32.71). Compared to this week last year (average trap count: 26.47) there has been a 23.57% increase in mosquito activity this week (average trap count: 32.71). The highest number of specimens caught in a single trap was 324 in North East Winnipeg (FSA: R2G) caught on June 21, 2024. The lowest number of specimens caught in a trap was 0. The highest city-wide average reported this week was 60.8 specimens on June 22, 2024, while the lowest city-wide average was 11.0 on June 18, 2024.

The week-over-week increase in mosquito activity can likely be attributed to several weeks of wet weather with high humidity, followed by hot weather (Baril et al., 2023).

A total of 8,375 mosquitoes were caught in city traps in week 25. The highest number of specimens was caught in traps outside of city limits (2,321 specimens). Within city limits, the quadrant with the highest number of specimens reported was Northeast Winnipeg (1,817 specimens). The quadrant with the lowest number of specimens was North West Winnipeg (1,396 specimens).

Historical Data

Mosquito trap counts are approaching 2015/2016 levels which saw the highest trap counts during week 25 for available data, but are currently most similar to trap counts observed in 2022.

Week-Year Summary Table

The following table displays the weekly mean trap counts for each year, coloured by row. Trap counts are currently at the highest in Week 25 since 2016 when the mean weekly trap count was 85. Currently, the trap counts are similar to those observed in 2022 and 2023.

Week	2015	2016	2017	2018	2019	2020	2021	2022	2023	2024
18	1.38	1.17	1.57	0.35	0.06	0.41	0.07	NA	NA	NA
19	0.20	2.48	0.17	0.27	0.09	0.22	0.09	0.23	0.95	0.58
20	0.22	0.30	0.35	0.20	0.15	0.13	1.27	0.04	1.01	0.20
21	1.15	2.68	0.33	0.73	0.12	0.51	1.57	0.19	4.33	0.26
22	2.66	0.96	0.42	1.16	0.21	0.77	1.41	0.44	7.69	2.63
23	53.42	2.64	2.70	3.43	2.47	5.72	5.90	2.64	3.83	6.72
24	73.48	69.57	0.60	4.99	4.70	2.00	9.23	13.53	5.73	20.19
25	36.05	84.95	0.39	16.54	2.33	5.15	14.31	31.25	26.47	32.71
26	42.28	34.42	0.94	11.48	3.88	51.71	26.86	16.68	18.67	NA
27	13.66	63.57	14.87	11.51	2.98	46.41	28.48	20.25	8.17	NA
28	11.38	27.52	12.25	22.49	4.51	37.46	11.01	30.33	6.73	NA
29	36.36	17.11	9.96	10.06	13.77	48.93	8.07	21.02	4.22	NA
30	48.68	30.09	6.31	6.02	79.64	34.61	6.00	13.70	6.20	NA
31	19.69	40.29	5.17	5.96	55.02	13.25	5.45	39.05	5.79	NA
32	38.77	43.63	2.62	11.99	22.28	10.43	2.75	83.27	3.88	NA
33	25.59	44.91	2.85	6.70	11.48	8.61	3.02	48.59	5.50	NA
34	12.81	24.37	2.12	6.53	7.90	7.95	1.53	33.38	4.05	NA
35	20.39	10.88	2.70	2.66	2.82	7.50	1.47	127.73	1.82	NA
36	28.36	10.06	0.86	1.74	1.57	1.24	3.44	32.48	1.44	NA
37	15.09	5.71	1.58	1.01	1.32	1.20	6.86	9.98	0.96	NA
38	7.72	NA	1.03	0.19	10.36	0.74	3.53	5.37	0.68	NA
39	11.54	NA	0.29	0.08	6.20	1.30	4.80	3.16	0.40	NA
40	NA	NA	NA	NA	NA	0.22	NA	NA	NA	NA

Distribution of Data

Mosquito trap counts tend to follow a poisson distribution, where there are many observations at zero or close to zero. This is most likely because mosquito activity occurs in bursts in response to favourable weather conditions including precipitation, humidity and temperature (Baril et al., 2023).

West Nile Virus

Manitoba Health carries out West Nile virus surveillance throughout the province by monitoring Culex tarsalis mosquitoes, the main vector for West Nile virus in Manitoba. To date, there have been no human cases of West Nile virus acquired in the province and no positive Culex tarsalis mosquito pools. Moreover, Culex tarsalis trap counts are low, but slowly increasing (Manitoba Health).

Data

If you are interested in this data, visit my interactive app here. If you are interested in receiving daily update notifications when the city updates their data, follow the Twitter account here.

References

Baril, C., Pilling, B.G., Mikkelsen, M.J. et al. The influence of weather on the population dynamics of common mosquito vector species in the Canadian Prairies. Parasites Vectors 16, 153 (2023). https://doi.org/10.1186/s13071-023-05760-x.

City of Winnipeg (2024). Nuisance Mosquito Trap Counts. https://legacy.winnipeg.ca/publicworks/insectcontrol/mosquitoes/trapcounts.stm.

City of Brandon (2024). Mosquito Abatement Program. https://brandon.ca/mosquito-abatement/mosquito-abatement-program.

Environment and Climate Change Canada (2024). WINNIPEG A CS Weather Station. https://climate.weather.gc.ca/climate_data/.

R Core Team (2023). R: A Language and Environment for Statistical Computing. R Foundation for Statistical Computing, Vienna, Austria. https://www.R-project.org/.

Python Software Foundation. (2024). Python Language Reference, version 3.10. Available at https://www.python.org.

Wickham H, Averick M, Bryan J, Chang W, McGowan LD, François R, Grolemund G, Hayes A, Henry L, Hester J, Kuhn M, Pedersen TL, Miller E, Bache SM, Müller K, Ooms J, Robinson D, Seidel DP, Spinu V, Takahashi K, Vaughan D, Wilke C, Woo K, Yutani H (2019). “Welcome to the tidyverse.” Journal of Open Source Software, 4(43), 1686. doi:10.21105/joss.01686 https://doi.org/10.21105/joss.01686.

Wickham H (2024). rvest: Easily Harvest (Scrape) Web Pages. R package version 1.0.4, https://CRAN.R-project.org/package=rvest.

Chang W, Cheng J, Allaire J, Sievert C, Schloerke B, Xie Y, Allen J, McPherson J, Dipert A, Borges B (2023). shiny: Web Application Framework for R. R package version 1.8.0, https://CRAN.R-project.org/package=shiny.

Pebesma E, Bivand R (2023). Spatial Data Science: With applications in R. Chapman and Hall/CRC. doi:10.1201/9780429459016 https://doi.org/10.1201/9780429459016, https://r-spatial.org/book/.

LaZerte S, Albers S (2018). “weathercan: Download and format weather data from Environment and Climate Change Canada.” The Journal of Open Source Software, 3(22), 571. https://joss.theoj.org/papers/10.21105/joss.00571.

Firke S (2023). janitor: Simple Tools for Examining and Cleaning Dirty Data. R package version 2.2.0, https://CRAN.R-project.org/package=janitor.

Grolemund G, Wickham H (2011). “Dates and Times Made Easy with lubridate.” Journal of Statistical Software, 40(3), 1-25. https://www.jstatsoft.org/v40/i03/.

Xie Y, Cheng J, Tan X (2023). DT: A Wrapper of the JavaScript Library ‘DataTables’. R package version 0.31, https://CRAN.R-project.org/package=DT.

Chang W (2021). shinythemes: Themes for Shiny. R package version 1.2.0, https://CRAN.R-project.org/package=shinythemes.

Roesslein, Joshua. (2024). Tweepy: Twitter for Python! Available at https://www.tweepy.org.

Reitz, Kenneth, & Chisom, Cory. (2024). Requests: HTTP for Humans [Software]. Available at https://docs.python-requests.org/en/latest/.

Cole Baril