Mosquito-Borne Disease Surveillance
The Maryland Department of Agriculture (MDA) and the Maryland Department of Health and Mental Hygiene (DHMH) collaborate to conduct a surveillance program to detect mosquito- borne viruses of public health concern. The program monitors the occurrence of Zika Virus, eastern equine encephalitis (EEE) virus, West Nile virus (WNV), and St. Louis encephalitis (SLE) and other viruses in mosquitoes, wild birds, domestic animals and humans. These viruses are maintained in nature in mosquito cycles. Isolation of viral presence in the mosquito cycle provides an early warning of virus transmission and is cause for increasing public awareness campaigns to reduce risk of disease and to take proactive steps for mosquito control to further reduce the risk to humans, domestic animals and zoo animals.
West Nile virus has affected every region of Maryland and is now considered as being endemic throughout the state.
Adult Mosquito Nuisance Control
The Department recognizes that the annoyance caused by moderate to large numbers of mosquitoes can adversely impact the quality of life for citizens and visitors in Maryland. Control of populations of nuisance mosquitoes in residential areas will be conducted in accordance with this policy.
Nuisance mosquito control will be provided only in residential areas (cities, towns, communities, individual residences) that specifically request mosquito control service and that cost-share to fund conduct of the program. The adult mosquito population must meet, or exceed, a minimum density to justify the application of pesticide. Two measurements of adult mosquito density are used in Maryland: (1) landing rate counts, and (2) light traps. The minimum landing rate threshold to initiate spraying of insecticide with ULV ground application equipment is 3 mosquitoes landing on an inspector in a 2-minute period. The minimum light trap collection to warrant ground spraying is 12 female mosquitoes, of a species known to feed on humans, per night. The minimum action thresholds for aerial application of an insecticide for nuisance adult mosquito control are: (1) an average landing rate count of 12 mosquitoes per minute; or (2) a light trap collection of 100 female mosquitoes per night.
It is preferred that landing rate and light trap criteria be used to evaluate the need for application of an insecticide. However, either method alone can be used. Aerial or ground spraying for adult mosquitoes will be done only when the minimum action threshold for landing rate counts or light trap collections is met or exceeded. The mosquito surveillance data must have been collected in the vicinity of the proposed treatment area within 48 hours prior to the treatment date. Service requests, i.e., complaints, from communities participating in mosquito control efforts do not provide sufficient justification for nuisance adult mosquito control. However, service requests will result in increased mosquito surveillance by mosquito control staff. An inspector will respond to a service request within two (2) business days after the request is received.
Mosquito spraying is not harmful to honeybees according to the MDA. According to the MDA Mosquito Control Website:
We are very concerned about the effects of our activities on non-target organisms, like honeybees and bats. We only conduct truck mounted spraying or misting at night. Bees are not active at night. The droplets in the spray have an extremely small diameter. The surface to mass ratio of these droplets is such that these droplets do not leave residue on surfaces. They are like tiny parachutes. When they are pulled down by gravity, drag keeps them from falling. The point is that these droplets do not land or stick on surfaces. When bees become active the next day and crawl across surfaces, those surfaces do not have any pesticide from our spray. The droplet size averages 15 micrometers. There are 1000 micrometers in a millimeter. We must have our machines tested, by law, twice a year.
Exclusions of Property from Nuisance Adult Mosquito Control Spraying
An individual may have his/her owned or leased property excluded from nuisance mosquito control. This exclusion will include a buffer of approximately 300 feet around the property. Each individual requesting this exclusion must submit the request in writing to the Department and provide a copy to the appropriate city, town, or county government. The individual may also notify the appropriate community association. The request must include the address of the property to be excluded from spraying and must be signed by the owner(s) or lessee(s). Annual updates are required of requests for exclusion from spraying. Click Here for the Adult Mosquito Control Exemption Form Mosquito Control Exemption Form
If the number of individual objectors and/or the location of the excluded property precludes an effective mosquito control adulticide service for a community, the service will be suspended. Adult mosquito control service may be reinstated to the community upon written request to the Department from the community association, town, city or county, if continuation of the mosquito control service is determined by the local authority to be in the best interest of the public. Because it is a cooperative program, the Department will defer to the local authority for the final decision relating to property exclusion policy. All disputes regarding this issue will be settled by the local authority. After service reinstatement, the Department will notify the individual who had requested the exclusion about the decision to reinstate service. The Department may attempt to exclude the application of insecticide immediately adjacent to the property of the person(s) requesting the exclusion, but will not provide a buffer around the property.
Adult Moqsuito Control to Protect Public Health from Mosquito-Borne Disease
West Nile encephalitis, eastern equine encephalitis, St. Louis encephalitis and Zika virus are mosquito-borne diseases that can adversely impact human health in Maryland. If any mosquito-borne disease becomes a real or imminent public health threat, adult mosquito control will be a priority issue. Under such conditions, spray exclusion zones will not be recognized and the action thresholds may be lowered. The department will exercise all means possible to reduce the adult mosquito population to the lowest level possible within the area where disease transmission to humans is a concern.
Tips to Rid Your Community of Mosquito Breeding Sites
- Clean rain gutters to allow water to flow freely.
- Remove old tires or drill drainage holes in tires used for playground equipment.
- Store plastic wading pools inside or turn them upside down when not in use.
- Turn over or remove clay pots and plastic containers.
- Dispose of all empty beverage containers, plastic wrappers, discarded toys, etc.
- Check for trapped water in plastic or canvas tarps used to cover boats, pools, etc. Arrange the tarp to drain the water.
- Pump out bilges in boats. Turn canoes and small boats upside down for storage.
- Replace water in bird baths at least twice a week.
- Remove pet food and water dishes that are not being used.
- Flush livestock water troughs twice a week.
- Don't leave garbage can lids lying upside down. Be sure water does not collect in the bottom of garbage cans.
- Flush water in the bottom of plant holders twice a week.
- Fix dripping outside water faucets.
- Turn wheelbarrows upside down when stored outside.
- Check around construction sites or do-it-yourself improvements to ensure that proper backfilling and grading prevent drainage problems.
- Check ornamental ponds, tree holes and water-holding low areas for mosquito larvae. Call the nearest Mosquito Control Office (see below) if you find, or suspect, mosquito larvae are present.
- If ditches do not flow and contain stagnant water for one week or longer, they can produce large numbers of mosquitoes. Report such conditions to a Mosquito Control Office. Do not attempt to clear these ditches because they may be protected by wetland regulations.
If you need assistance locating breeding areas around your house, or would like to report stagnant water near your property call the Department of Public Works at 301-725-0088 or you may e-mail Public Works at [email protected]. You can also watch the Mosquito Control workshop on the City’s cable station. Laurel cable can be found on Comcast, Channel 71 or Verizon FIiOS, Channel 12. The workshop has many helpful ways to combat mosquito problems in your community.
The Maryland Department of Agriculture Mosquito Control Office can be contacted at 301-422-5080.