Press Enter to show all options, press Tab go to next option
Select a News Category OR a Department to narrow the News listing.

Mosquito Spraying by County Scheduled for Lower Merion

Post Date:09/13/2018 5:00 PM

The Montgomery County Office of Public Health (OPH) plans to conduct adult mosquito control in a section of Ardmore south of Lancaster Avenue, due to West Nile Virus positive mosquito collections in the area (see map below). The spraying will take place on Thursday, Sept. 20th, with a rain date of Thursday, Sept. 27th. The application will begin at about 7:45 p.m. and end around 11:30 p.m. Mosquito spraying, Ardmore, September 2018

In addition, adult mosquito control spraying is scheduled for Ashbridge Park in Rosemont on the evening of Monday, Sept. 24th.

All spraying will be performed by OPH personnel using an OPH identified truck-mounted ultra-low volume (ULV) sprayer. Individuals listed in the Pesticide Hypersensitivity Registry, and registered apiaries within 500 feet of the spray area, will be notified by the Montgomery County Health Department.

In late August, the County announced that the OPH was investigating two probable cases of West Nile Virus involving a 66-year-old resident of Lower Merion Township and a 59-year-old resident of Montgomery Township. Both cases were sent for further testing to the Centers for Disease Control and Prevention (CDC). In 2016, there were 16 confirmed human cases of WNV throughout the Commonwealth of Pennsylvania, of which two were Montgomery County residents.

For updated information, click here: Below is an FAQ sheet for the public issued by the County.

Ashbridge spray area on Google Map*


Montgomery County Office of Public Health (OPH)

 Frequently Asked Questions regarding Mosquito Spraying


Why is my neighborhood being sprayed?

The OPH conducts sprays in areas where West Nile Virus (WNV) infected mosquitoes threaten human health. It is well documented that reducing populations of mosquitoes decreases the possibility of being bitten by an infected mosquito.

How does OPH determine which areas are being sprayed?

If mosquito surveillance and testing show that there is a threat to human health, OPH may initiate a spray to control adult mosquitoes. OPH does not conduct nuisance mosquito control or take requests from the public for mosquito spraying. 

How do I get my neighborhood tested?

The OPH conducts adult mosquito surveillance throughout the county. However, we are always looking for additional areas to test. If you believe your neighborhood needs to be tested and would allow OPH to conduct surveillance on your property, please contact the OPH location closest to you.

Do the pesticides used during the spraying hurt people and pets?

OPH conducts spraying carefully and follows all state and federal requirements. Most people and their pets do not have health effects during or after the spraying. Some people are more sensitive to the pesticides and are notified before the spraying occurs. If you have effects from the spraying, please contact your doctor.

Who is actually doing the spraying?

Spraying is conducted by certified OPH personnel. On occasion, the Pennsylvania Department of Environmental Protection (DEP) will assist the OPH with mosquito sprays.

Should I remain indoors during the spray?

It is the recommendation of the OPH to stay indoors during a mosquito spray event and remain indoors for 15-20 minutes after the truck sprays your immediate area.

Should I close my windows and turn off air conditioner units?

OPH recommends closing windows and turning off fans that bring outside air into your home. If your window or central a.c. unit can be switched to only recirculate and cool air within your home, it is safe to leave it on. 

How far does the spray travel?

The spray can travel up to 300 feet from the source and still be effective on mosquitoes. Depending on the wind and air currents, spray residual could travel farther but not in concentrations that would be effective for mosquito control.

Should my pet remain indoors during a spray?

The mosquito control products used by the OPH are considered safe for animals and pets when used properly. However, if you wish to limit your pet’s exposure, keep them indoors.

Should I take special precautions for my garden?

There is nothing you have to do to fruit or vegetable gardens. OPH recommends washing your fruits and vegetables prior to cutting and/or consuming them.

Should I take special precautions for my swimming pool?

Your swimming pool and items in your yard should not be affected by mosquito spraying conducted at the proper label rates. Mosquito control products are applied at ultra-low volume (ULV) rates, generally below one ounce/acre, and rapidly break down in sunlight. However, some people choose to cover pools and other items as a precaution.

How are the pesticides applied?

All adult mosquito control events conducted in Montgomery County are performed with ultra-low volume (ULV) application equipment mounted on a truck, ATV or hand held. Residents can refer to press releases issued by the OPH to find out what equipment is being used for a specific spray.

Why do you choose to spray at that time?

Mosquito sprays only kill mosquitoes that are actively flying during the spray event. We start at dusk, because research has shown that the mosquitoes involved in WNV transmission begin activity at dusk and are the most active for the next three hours.

How many species of mosquitoes are there?

There are currently 62 species of mosquitoes in Pennsylvania. Many of those can be found in Montgomery County. Thankfully, only a fraction of the mosquito species found in Montgomery County are a potential WNV threat. The OPH targets those species that pose a risk of spreading WNV.

Will the spray kill all of the mosquitoes in my neighborhood?

Mosquito sprays will only reduce the population of mosquitoes in a given area. There are many factors that contribute to the success of any mosquito spray. Truck mounted sprays are limited by the vehicle’s ability to access all of the areas within a selected spray zone. Weather conditions, such as temperature and wind speed, will also affect how successful a mosquito spray will be. Only those mosquitoes actively flying during a spray event have the potential to be killed.

Are there any weather conditions that will postpone a spray?

Rain, winds under 1 MPH and over 10 mph. or temperatures below 55°F will each cause the postponement of a mosquito spray event.

Does OPH notify residents in advance of mosquito spray events?

The OPH notifies residents in several ways.

  1. A press release is issued for all adult mosquito sprays in Montgomery County at least 48 hours in advance.
  2. Individuals listed on the PA Department of Agriculture, Pesticide Hypersensitivity Registry and registered bee keepers within 500 feet of a spray area are personally notified prior to the event.
  3. Residents who would like to be notified of when spraying will occur should sign up for the ReadyMontco alerts at ReadyMontco replaced the ReadyNotifyPA system in June 2015. There are no longer “health” alerts. Residents need to sign up for county alerts and municipal alerts for the jurisdiction in which they reside.

All local municipalities that are within a mosquito spray area are consulted and given detailed information about the spray.

How do I find out more information about the OPH Mosquito-borne Disease program?

More information regarding the OPH mosquito-borne disease program can be found at:


Free viewers are required for some of the attached documents.
They can be downloaded by clicking on the icons below.

Acrobat Reader Flash Player Windows Media Player Microsoft Silverlight Word Viewer Excel Viewer PowerPoint Viewer