Mosquito Control

Mosquito spraying is done on as needed basis. That determination is based on mosquito counts and/or requests by citizens. To report mosquito activity in your neighborhood, please call 361.777.4601.  

The chemicals must make contact with the mosquitoes to be effective, so spraying is scheduled in the early morning and late evening, when mosquitoes are most active. Normal spraying times begin at 4:00 a.m. and at 8:00 p.m. Wind and weather conditions affect the effectiveness of mosquito control efforts. If winds are too strong or in wet conditions, spraying is not effective and may be rescheduled. 

Please see the current spraying schedule below. Spraying schedules from previous months are posted below the current schedule. You can find the spraying route map and information on the chemicals used for spraying below, as well. 

SCHEDULE (UPDATED MaY 6, 2022)

DATE ROUTE TIME REMARKS
May 5, 2022   1 - 4 AM/PM Larvicidal surveillance and treatment
May 4, 2022   1 - 4 AM Larvicidal surveillance and mosquito counts
March 10, 2022  1 - 4 AM/PM Larvicidal surveillance and treatment
October 27, 2021  1 - 4   Rain event
October 26, 2021  1 - 4 AM Larvicidal treatments and mosquito counts
October 25, 2021  1 - 4 PM Larvicidal treatments and mosquito counts
October 22, 2021  1 - 4 PM Scheduled spot spraying from 7 PM to 9 PM
October 21, 2021  1 - 4 PM Scheduled spot spraying from 7 PM to 9 PM
October 20, 2021  1 - 4 PM Larvicidal treatments and mosquito counts
October 19, 2021  1 - 4 AM Larvicidal treatments and mosquito counts
October 18, 2021  1 - 4 PM Scheduled spot spraying citywide from 7 PM to 9 PM
October 18, 2021  1 - 4 AM/PM Larvicidal treatments and mosquito counts
October 15, 2021  1 - 4 PM Scheduled larvicidal surveillance and treatments
October 14, 2021     Rain event.
October 13, 2021  1 - 4 AM Larvicidal surveillance and mosquito counts
October 12, 2021  1 - 4 AM Scheduled spot spraying from 5 AM to 9 AM
October 11, 2021  1 - 4 AM Surveillance and mosquito counts
October 8, 2021  1 - 4 PM Larvicidal treatments and mosquito counts
October 7, 2021  1 - 4 PM Scheduled spot spraying from 7 PM to 9 PM
October 7, 2021  1 - 4 AM/PM Larvicidal treatments and mosquito counts
October 6, 2021  1 - 4 PM Scheduled spot spraying citywide from 7 PM to 9 PM
October 6, 2021  1 - 4 AM Larvicidal treatments and mosquito counts
October 5, 2021  1 - 4 AM/PM Scheduled larvicidal surveillance and treatments
October 4, 2021  1 - 4 AM/PM Scheduled larvicidal surveillance and treatments
October 1, 2021     Rain event
September 30, 2021     Rain event
September 29, 2021     Rain event
September 28, 2021     Rain event
September 24, 2021  1 - 4 AM Larvicidal treatments and mosquito counts
September 17, 2021  1 - 4 AM Larvicidal treatments and mosquito counts
September 15, 2021  1 - 4 AM/PM Scheduled larvicidal surveillance and treatments
September 14, 2021  1 - 4 PM Scheduled larvicidal surveillance and treatments
September 13, 2021     Rain event
September 12, 2021     Rain event
September 9, 2021  1 - 4 AM Scheduled larvicidal treatments and mosquito counts
September 7, 2021  1 - 4 AM Conducted surveillance
September 3, 2021   AM Rain event
August 31, 2021  1 - 4 AM/PM Scheduled larvicidal treatments and mosquito counts
August 30, 2021  1 - 4 PM Initiated larvicidal surveillance and treatments
August 28, 2021     Rain event
August 27, 2021     Rain event
August 26, 2021     Rain event
August 20, 2021  1 - 4 AM Conducted surveillance
August 16, 2021  1 - 4 PM Initiated larvicidal surveillance and treatments
August 16, 2021     Rain event
August 14, 2021     Rain event
July 23, 2021  1 - 4 AM Conducted larvicidal treatments and mosquito counts
July 22, 2021  1 - 4 AM Conducted larvicidal treatments and mosquito counts
July 21, 2021  1 - 4 PM Scheduled spot spraying citywide from 8 PM to 10 PM
July 21, 2021  1 - 4 AM/PM Conducted larvicidal treatments and mosquito counts
July 20, 2021     Rain event
July 19, 2021  1 - 4 PM Scheduled spraying citywide from 8 PM to 11:30 PM
July 19, 2021   1 - 4 AM/PM Conducted larvicidal treatments and mosquito counts
July 17, 2021  1 - 4 PM Scheduled spot spraying citywide from 8 PM to 10 PM
July 15, 2021  2 & 3 AM Scheduled spraying citywide from 5 AM to 7:30 AM
July 15, 2021  1 & 4 PM Scheduled spraying citywide from 8 PM to 10:30 PM
July 14, 2021  1 - 4 AM Conducted larvicidal treatments and mosquito counts
July 13, 2021  1 - 4 PM Scheduled spraying citywide from 8 PM to 12 AM
July 13, 2021   AM Rain event
July 12, 2021  1 - 4 PM Scheduled spraying citywide from 8 PM to 12 AM
July 12, 2021  1 - 4 AM Conducted larvicidal surveillance, treatments, and mosquito counts
July 9, 2021  1 - 4 PM Initiated larvicidal surveillance and treatments
July 1 - 9, 2021     Rain events
June 30, 2021     Rain event
June 25, 2021     Conducted larvicidal surveillance and treatments
June 23, 2021   AM Rain event
June 21, 2021   AM Rain event
June 20, 2021   PM Rain event
June 15, 2021     Conducted larvicidal surveillance and treatments
June 11, 2021  1 - 4 PM Conducted larvicidal surveillance and treatments
June 10, 2021  1 - 4 PM Conducted larvicidal surveillance and treatments
June 7, 2021  1 - 4 AM Conducted larvicidal surveillance and mosquito counts
June 4, 2021  1 - 4 PM Conducted larvicidal surveillance and treatments
June 4, 2021   AM Rain event
June 3, 2021   PM Rain event
June 2, 2021  1 - 4 PM Scheduled spraying citywide from 8 PM to 11 PM
June 1, 2021     Rain event
May 30, 2021     Rain event
May 29, 2021     Rain event
May 28, 2021     Conducted mosquito counts and larvicidal treatments
May 27, 2021     Conducted mosquito counts, spot spraying, and larvicidal treatments
May 26, 2021  1 - 4 AM/PM Conducted mosquito counts, spot spraying, and larvicidal treatments
May 25, 2021  1 - 4 PM Scheduled spraying from 7:30 PM to 11 PM as wind conditions allow
May 25, 2021  1 - 4 AM Conducted mosquito counts, spot spraying, and larvicidal treatments
May 24, 2021  1 - 4 PM Scheduled spraying citywide from 7:30 PM to 11 PM
May 24, 2021  1 - 4 AM Conducted mosquito counts, spot spraying, and larvicidal treatments
May 23, 2021     Rain event
May 21, 2021  1 - 4 PM Conducted larvicide surveillance and treatments
May 19, 2021     Rain event
May 18, 2021     Rain event
May 16, 2021     Rain event
May 15, 2021     Rain event
May 14, 2021  1 - 4 AM/PM Conducted larvicide surveillance and treatments
May 13, 2021  1 - 4 PM Conducted mosquito counts and spot spraying
May 13, 2021  1 & 4 AM Conducted larvicide surveillance and treatments
May 11, 2021     Rain event
May 11, 2021  1 & 4 AM Scheduled spraying from 5 AM to 7:30 AM
May 10, 2021  2 & 3 PM Scheduled spraying from 8 PM to 10:30 PM
May 9, 2021     Spraying rescheduled due to strong winds.
May 8, 2021  2 & 3 AM Scheduled spraying from 5 AM to 7:30 AM
May 7, 2021  1 & 4 PM Scheduled spraying from 8 PM to 10:30 PM
May 7, 2021  1 - 4 AM Conducted mosquito counts and spot spraying
May 6, 2021  1 - 4 AM/PM Conducted larvicide surveillance and spot spraying
May 5, 2021  1 - 4 AM/PM Conducted larvicide surveillance and treatments
May 3, 2021  1 - 4 PM Conducted larvicide surveillance and treatments
May 1, 2021     Rain event
April 30, 2021     Rain event
April 28, 2021  1 - 4 PM Conducted larvicide surveillance and treatments
April 14, 2021  1 - 4 PM Conducted larvicide surveillance and treatments
April 6, 2021  1 - 4 PM Conducted larvicide surveillance and treatments
March 25, 2021  1 - 4 PM Conducted larvicide surveillance and treatments
March 12, 2021  1 - 4 PM Conducted larvicide surveillance and treatments
February 9, 2021  1 - 4 PM Conducted larvicide surveillance and treatments
January 29, 2021  1 - 4 PM Conducted larvicide and mosquito counts - afternoon spraying targeting ditches, parks, and ROWs
January 14, 2021  1 - 4 PM Conducted larvicide surveillance and treatments
January 10, 2021   AM/PM Rain event
       
December 21, 2020  1 - 4 PM Conducting larvicide treatments and spot spraying in ditches
December 15, 2020     Conducted surveillance and mosquito counts
November 20, 2020     Conducted surveillance and mosquito counts
November 9, 2020    AM Conducted mosquito counts
November 6, 2020    AM/PM Conducted mosquito counts
October 28, 2020    AM Rain event
October 26, 2020   1 - 4  PM Conducted surveillance and larviciding
October 23, 2020   1 - 4  AM  Conducted mosquito counts
October 19, 2020   1 - 4  AM/PM Conducted surveillance and larviciding
October 16, 2020   1 - 4  AM Conducted mosquito counts
October 14, 2020   1 - 4  AM Conducted spot spraying
October 13, 2020   1 & 4  AM Scheduled spraying from 4 AM to 7 AM
October 12, 2020   2 & 3  PM Scheduled spraying from 8 PM to 11 PM
October 12, 2020   1 - 4  AM Conducted mosquito counts and larviciding
October 9, 2020   1 - 4  AM Conducted mosquito counts
October 7, 2020   1 - 4  AM Conducted mosquito counts
October 6, 2020   1 & 4  AM Scheduled spraying from 4 AM to 7 AM
October 5, 2020   2 & 3  PM Scheduled spraying from 8 PM to 11 PM
October 5, 2020   1 - 4  AM Conducted larviciding and mosquito counts
October 2, 2020   1 - 4  PM Conducting spot spraying
October 2, 2020   1 - 4  AM Conducted mosquito counts and spot spraying in alleys and ditches
October 1, 2020   1 - 4  PM Conducted mosquito counts in parks, alleys, and ditches
September 28, 2020   1 - 4  AM Conducted larviciding and mosquito counts
September 25, 2020   1 - 4  PM Conducted larviciding and mosquito counts
September 25, 2020   1 & 4  AM Scheduled spraying from 5 AM to 7 AM
September 24, 2020   2 & 3  PM Scheduled spraying from 8 PM to 10 PM
September 24, 2020   1 - 4  AM Conducted larviciding and mosquito counts
September 23, 2020   1 - 4  PM Scheduled spraying from 8 PM to 10 PM, targeting ditches and parks
September 23, 2020   1 - 4  AM/PM Conducted larviciding and mosquito counts
September 22, 2020   1 - 4  AM/PM Conducted surveillance and larviciding
September 21, 2020    AM/PM Rain event
September 19, 2020   1 - 4  AM Scheduled spraying from 4 AM to 7 AM
September 18, 2020   1 - 4  AM Performed scheduled spraying from 4 AM to 7 AM
September 17, 2020   1 - 4  PM Rain event
September 17, 2020   1 - 4  AM Conducted larviciding, mosquito counts, and day spraying
September 16, 2020   1 - 4  PM Scheduled spraying from 8 PM to 11 PM, weather pending
September 16, 2020   1 - 4  AM Larviciding and mosquito counts
September 15, 2020   1 - 4  AM/PM Larviciding and spraying in high count areas
September 14, 2020    PM Rain event
September 11, 2020   1 - 4  AM/PM Conducted larviciding and some spot spraying in high count areas
September 10, 2020    AM Rain event
September 9, 2020   1 - 4  AM/PM Conducting mosquito counts and day spraying
September 9, 2020    AM Rain event
September 8, 2020   1 - 4  AM/PM Conducted larviciding, mosquito counts, and some spot spraying
September 2, 2020   1 - 4  AM Larviciding and mosquito counts
September 1, 2020   1 - 4  AM Larviciding and mosquito counts
August 31, 2020   1 - 4  PM Larviciding and mosquito counts
August 28, 2020   1 - 4  PM Larviciding and mosquito counts
August 26, 2020   1 - 4  AM/PM Scheduled larviciding and mosquito counts
August 25, 2020   1 - 4  PM Larviciding and mosquito counts

Spraying Logs from Previous Months
- Mosquito Control Spraying Log - June 2020
- Mosquito Control Spraying Log - July 2020
- Mosquito Control Spraying Log - August 2020

Map of Spraying Routes
Portland is separated into four areas for mosquito spraying.
Mosquito Spraying Route

The City uses two adulticides--Mosquitomist ONE ULV and Biomist 4+4 ULV.

Mosquitomist Safety Data         Biomist Safety Data