As if a pandemic wasn’t enough for 2020, the East Side Mosquito Abatement District has now identified a brand new threat to the area – the yellow fever mosquito has landed in Modesto and is expanding its reach to Stanislaus County.
The new mosquito species, Aedes aegypti, was caught in Modesto in July and is in the same vector as the Zika, Dengue and Chikungunya viruses.
This new mosquito, unlike other Aedes mosquitoes that grow in pasture, grows in small containers in residential areas and often in houses. It bites people only and does so during the day.
While it may be unsettling to some to discover a new species of mosquito that may carry a dangerous virus, residents may have noticed how many pesky bloodsuckers swarm unsuspecting hosts the moment they step outside.
“We have received a total of 149 service requests from Oakdale since the beginning of September. The majority of these calls came in within the last two weeks, ”said Dr. J. Wakoli Wekesa, East Side Mosquito District Manager / Entomologist, with Abatement District. “There were 70 calls to the Valley Home region and 31 calls were made north of the Stanislaus River, east to Knights Ferry. The high volume coincided with the shaking of almond trees in the northwest and mainly around the town of Oakdale and was made worse by the prevailing wind that was forcing mosquitos into the town. “
In case you thought you imagined the flood of mosquitoes, you weren’t – the hungry mosquito population had indeed exploded, causing aggressive swarming in the parks and near water.
It’s a problem every year that causes the East Side Mosquito Abatement District to make calls and send out abatement teams to address problem areas.
According to Dr. Wekesa, the district has a proactive program to conduct mosquito surveillance – trapping adults and monitoring the presence of larvae and adult mosquitoes in the area so they can act before a major mosquito problem occurs. Monitoring is carried out once a week, the mosquitoes caught are identified and tested for the West Nile virus. The other mosquito control program consists of operations that involve two technicians, one focused on finding aboveground brood sources and applying larvicides to control them before they hatch, and the other one focused on the subsurface with a technician Performs curb rigging operations to control mosquitoes in underground storm drains, canals and swallows in parks, ditches and underground road systems.
“Every now and then, when adult mosquitoes are on the rise in the neighborhood, especially in nearby orchards, the district will run sprays of adulticides to kill adult mosquitoes so people in town won’t get bitten,” said Dr. Wekesa. “We also have two planes that the district uses to spray open fields on the outskirts of the city to reduce the bite pressure on people. The service request over the past two weeks was a flare-up of adult mosquitoes from almond plantations in the northwest of the city and also along the Stanislaus River. “
Spraying larvicides is an on-going process to keep mosquito populations down. However, for the past two weeks, the district has had to perform an ultra-low volume spray in the town of Oakdale using two truck-mounted sprayers on three mornings between 4 a.m. and 7:30 a.m. September 16-18.
“We sprayed mostly the north and north-west sides of Oakdale on the morning of September 16 and 17 and the south-west, south and north-east sides on September 17 and 18,” said Dr. Wekesa. “A total of 390 acres were sprayed in the three mornings, and we believe that relief has been created in these parts of the city.”
The district has been trapping mosquitoes across the district on a weekly basis since April 1, including more than seven locations in the Oakdale area. West Nile virus has been identified in 12 pools of mosquitoes (each pool or sample has 10-50 mosquitoes), the first mosquito sample to test positive for WNV was collected on July 10, and the last was collected on August 13.
Dr. Wekesa said: “The high temperatures, especially the nighttime temperature of over 68 ° F, which started in early July through September 6th, posed a particular risk that increased the transmission of this disease by mosquitoes.”
There have been several cases of West Nile virus in humans in the district and three cases in the Oakdale area and two cases of WNV in horses.
“This has been a tough year for all of us, and especially for the residents of our county and surrounding counties,” said Dr. Wekesa too.
To control mosquito infestation, it is important to remove standing water to avoid optimal breeding sites.
“Mosquitoes need standing water in order to grow. If there is no standing water, there are no mosquitos. Anything people can do to reduce stagnant water to no more than three days is sure to make a huge difference in our quality of life, ”said Dr. Wekesa. “Because of our agriculture, which is heavily dependent on irrigation water, this water, which often stands for weeks, creates an important unnatural source for mosquito breeding. The Mosquito Control Act gives the district the ability to control such property owners. Control of mosquitoes results in penalties for the properties that produce mosquitos. The remedy has never been used before. However, as the district faces increasing challenges in protecting its residents, such an approach can become a viable last resort. “
District residents pay taxes to perform mitigation services. The East Side Mosquito Abatement District was established on July 28, 1939 when agriculture and mosquito control faced different challenges. The district’s resources are currently adequate but lean. Before the pandemic hit, the district was in the process of asking voters for a benefit assessment by voting. These plans have been deferred to such a point that they are conducive to such a request.
Due to the scarcity of resources, the district must work with residents to deter mosquito populations in their neighborhood. First, irrigation districts and cities need to be proactive in cleaning up leaks from water pipes and repairing ditches or drains as quickly as possible. Farmers can be considerate and only use water that is necessary during the irrigation cycle provided to them. Also, report standing water to the district and speak to neighbors to reduce irrigation water to what is necessary.
Individual residents can proactively remove containers, broken chairs, boats, and other items that may contain water. Clean and maintain swimming pools and maintain sprinklers.
For more information on mosquito control or to report an infestation, please contact East Side Mosquito Abatement at (209) 522-4098.