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 AUGUST 6, 2020)

DATE ROUTE TIME REMARKS
August 6, 2020   1 - 4  PM Perform surveillance in previous high mosquito count areas
August 6, 2020   1 - 4  AM Performed mosquito counts and some spot spraying in
parks, ditches, and fields
August 5, 2020   1 - 4  PM Scheduled mosquito counts and spot spraying
August 5, 2020   1 - 4  AM Performed mosquito counts and some spot spraying in
parks, ditches, and fields
August 4, 2020   1 - 4  PM Scheduled residential spraying citywide
August 4, 2020   1 - 4  AM Mosquito counts still high. Daytime spot spraying continues
August 3, 2020   1 - 4  PM Schedule residential spraying citywide at maximum allow-
able flow rate in accordance with product label
August 3, 2020   1 - 4  AM Mosquito counts high. Daytime spraying underway
August 1, 2020     Rain event
August 1, 2020   1 - 4   Performed mosquito counts and mid-morning spraying. 
Rain in forecast
August 1, 2020   1 & 3  AM Scheduled residential spraying
July 31, 2020   2 & 4  PM Scheduled residential spraying
July 31, 2020   1 - 4  AM Larviciding, mosquito counts, and daytime spraying underway
July 30, 2020   1 - 4   Larviciding, mosquito counts, and daytime spraying underway
July 29, 2020   1 - 4   Surveillance/larviciding underway
July 27, 2020   1 - 4   Surveillance/pretreatment underway
July 25-26, 2020     Rain event - Hurricane Hanna

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