Where does the city spray, and how often?
Asked August 25, 2026 Figures as of October 12, 2026
Nearly every zone, a few zones a night, in July. The city has sprayed on 34 nights so far in 2026 and recorded 131 treatments on them, about 4 zones a night, from Jun 8, 2026 to Sep 14, 2026; the season is still open as of Oct 12, 2026. 2024, the first season in the record, had 37 nights and 178 treatments, and through Sep 14 of each year the seasons stood at 112 (2025) and 175 (2024) against 131 this year. July holds 49% of every treatment on record, and 72% of the treatments with a recorded time start in the 8 p.m. hour. Treatment counts in 2026 run from 1 to 8 per zone: 3 zones tie at 8, sprayed every 9 to 14 nights, 8 of the 25 zones sprayed sit within one treatment of them, and 25 of the city's 26 zones were sprayed at all. What changed in 2026 is the product: 96% of treatments used MosquitoMist Ultra, against 4% the season before.
Season by season
| Season | Nights | Treatments | Zones | Per night | First | Last | Ultra |
|---|---|---|---|---|---|---|---|
| 2026 | 34 | 131 | 25 | 4 | Jun 8, 2026 | Sep 14, 2026 | 96% |
| 2025 | 31 | 122 | 26 | 4 | Jun 16, 2025 | Sep 25, 2025 | 4% |
| 2024 | 37 | 178 | 22 | 5 | Jun 3, 2024 | Sep 24, 2024 | 8% |
Zone by zone, 2026
Treatments this season, the median nights between them, and the median hours from spray start to the recorded reopening.
| Zone | Treatments | Nights between | Closed for |
|---|---|---|---|
| Zone 05 | 8 | 9 | 11.6 h |
| Zone 11 | 8 | 14 | 4.5 h |
| Zone 15 | 8 | 13 | 4.3 h |
| Zone 02 | 7 | 13 | 4.6 h |
| Zone 04 | 7 | 13 | 4.3 h |
| Zone 14 | 7 | 14.5 | 4.7 h |
| Zone 17 | 7 | 11 | 11.6 h |
| Zone 18 | 7 | 13 | 11.4 h |
| Zone 07 | 6 | 13 | 8.1 h |
| Zone 19 | 6 | 14 | 11.5 h |
| Zone 01 | 5 | 10.5 | 11.7 h |
| Zone 03 | 5 | 14 | 11.8 h |
| Zone 08 | 5 | 10.5 | 11.8 h |
| Zone 13 | 5 | 14.5 | 11.8 h |
| Zone 16 | 5 | 14 | 11.0 h |
| Bike Trail | 4 | 17 | 9.9 h |
| Renner | 4 | 21 | 3.4 h |
| Revilo Pl | 4 | 12 | 8.0 h |
| Zone 09 | 4 | 26 | 8.9 h |
| Zone 10 | 4 | 16 | 11.3 h |
| Zone 12 | 4 | 29 | 13.8 h |
| Zone 20 | 4 | 11 | 16.7 h |
| Landfill | 3 | 19.5 | 12.6 h |
| Zone 06 | 3 | 27.5 | 11.4 h |
| Golf Course | 1 | — | 3.1 h |
By month and by hour
| June | 107 |
| July | 212 |
| Aug | 75 |
| Sept | 37 |
| 12 a.m. | 2 |
| 8 a.m. | 12 |
| 9 a.m. | 1 |
| 7 p.m. | 43 |
| 8 p.m. | 278 |
| 9 p.m. | 26 |
| 10 p.m. | 17 |
| 11 p.m. | 6 |
Method
Counted: every Treatment in the city's spray record, 431 across 26 zones since Jun 3, 2024. A season is a calendar year; a night is a calendar day in the record's own clock, read as local wall-clock time (ADR-0010). "Zones treated" counts the city's named areas, including the greenway and the areas the city names but draws no boundary for. A zone entered twice on one night counts twice; 4 such rows exist across the record, and the season the figures date falls in is counted as it stands, not as a finished season.
Nights between treatments is the median gap between one treatment of a zone and the next in the same season. Closure hours use the 411 treatments whose recorded reopening follows the start by no more than 72 hours; 6 closures precede their own start and 14 run past 3 days, and both are treated as entry errors and left out. Start hours leave out the 46 treatments entered at an exact 08:00, which the Section reads as a default rather than a time.
Sources
- Mosquito Spray as of October 12, 2026