West Chester Borough residents request free larvicide here. Other municipalities: please do similarly to help cut down on mosquito populations without harming other species.
Mosquito control
WEST CHESTER BOROUGH MOSQUITO ABATEMENT ACTION PLAN
In May 2019, West Chester Borough officially adopted a well-conceived mosquito abatement plan relying on controlling stagnant water and larviciding where needed. The text can be downloaded here in official form and also is copied below:
Regarding the spread of disease, such as West Nile Virus, through mosquitos, the Borough of West Chester has tasked the Public Works Department to implement the following action plan which replaces all other mosquito/West Nile Virus plans:
• The attainment of Larvicide Applicator Certification by at least two Public Works employees.
• Continue to store adequate quantity of dunks at its facility to be made available to Borough residents at their request.
• Elimination of all sumps from existing inlets inspected and found to facilitate ponding.
• Re-double its efforts to keep inlets clean and clear of debris that might inhibit proper drainage.
• Establish GIS mapping of current low-lying areas that are deemed susceptible to water ponding.
• Identify locations within the Borough that are potential “hot spots” for mosquito breeding for additional investigation by the Public Works Department.
• All activities must be consistently coordinated in concert with Chester County Health Department (CCHD) protocol.
• Constant communication must be kept with the CCHD as this will further enable the Public Works Department to be pro-active with on-going responses, by their ability to provide more detailed inspection and identification of potential breeding grounds.
• Direct residents who observe standing water on properties to call Building, Housing & Code Enforcement at 610-696-1773.
Q&A: What can we do to reduce the mosquito population?
Updated May 9, 2021. Short version: dump standing water; larvicide water that can’t be dumped.
Here is the enemy: 
But that photo shows mosquito larvae, which don’t bite.
Right, but once larvae hatch, they are harder to control. One female mosquito, with a protein infusion from blood, lays 100+ eggs. The eggs hatch into larvae, which fly away as adults in a few days. Continue reading
Do we still have mosquitoes in very late September?
Unfortunately, yes! And they seem hungry, trying to get in another generation or two before cold weather.
Please let’s all be out the lookout for standing water, as pictured here in a photo taken 3 days ago, and dump it out! The larvae stand out most clearly on the pink background at top center:
Petition to your public officials to end mosquito spraying from Beyond Pesticides
See background write-up and sign the petition here. The Don’t Spray Me! board has approved signing on as an organization; please add your individual signature as well. The text of the petition is below. The URL at the very end downloads the pdf of “PUBLIC HEALTH MOSQUITO MANAGEMENT STRATEGY For Decision Makers and Communities,” a very thorough summary of issues related to mosquito control and spraying.
Mosquito spray programs, which target flying mosquitoes with highly toxic organophosphate or synthetic pyrethroid insecticides, are ineffective and endanger our health. These pesticides, which are generally applied as ultra-low-volume (ULV) formulations, will float in the air longer than usual because of their small droplet size, but will eventually land on lawns, gardens, and anything that is outside. That droplet size also allows them to be carried deeper into the lungs. These pesticides can cause a wide range of health effects in humans, including exacerbating respiratory illness like Covid-19, and harm our environment.
Symptoms of organophosphate poisoning in humans include numbness, tingling sensations, headache, dizziness, tremors, nausea, abdominal cramps, sweating, incoordination, blurred vision, difficulty breathing, slow heartbeat, loss of consciousness, incontinence, convulsions, and death. Some organophosphates have been linked to birth defects, cancer, and brain effects. Symptoms of synthetic pyrethroid poisoning include dermatitis and asthma-like reactions, eye and skin irritation, and flu-like symptoms. Synthetic pyrethroids are endocrine disruptors and have been linked to breast and prostate cancer. People with asthma and pollen allergies should be especially cautious. Exposure has resulted in deaths from respiratory failure.
Naled, an organophosphate commonly used for mosquito control, affects a variety of non-target animals, including fish, insects, aquatic invertebrates, and honey bees. Naled is moderately acutely toxic to mammals, moderately to very highly toxic to freshwater fish and birds, highly toxic to honey bees, and very highly toxic to freshwater aquatic invertebrates, and estuarine fish and invertebrates. Elevated mortality rates among honey bees have been documented after nighttime aerial ULV applications of naled. Synthetic pyrethroids are highly toxic to fish and honey bees, even in low doses. Beneficial insects, including mosquito predators like dragonflies, will be killed by synthetic pyrethroids and organophosphates.
In addition to the dangers, spraying to kill adult mosquitoes (adulticiding) is the least effective mosquito control method. Close to 99.9% of sprayed chemicals goes off into the environment where they can have detrimental effects on public health and ecosystems, leaving 0.10% to actually hit the target pest. In addition, efforts to control the transmission of mosquito-borne diseases are encountering a big, though predictable, problem—mosquitoes are developing resistance to insecticides.
There are better ways to manage mosquito problems. Outbreaks of disease-carrying mosquitoes often result from habitat disturbance, such as deforestation, impairing wetlands, and spraying insecticides. Restoring the health of ecosystems helps keep mosquitoes under control. Native minnows, for example, can provide effective control of mosquito larvae breeding in standing water. Where water cannot be emptied from containers, the bacterial larvicide Bacillus thurigiensis israelensis is a least-toxic option. A better mosquito management plan protects public health and the environment. Please tell our local and state health departments to abandon spraying and adopt a mosquito management plan that does not depend on toxic chemicals: bp-dc.org/mosquito-mgmt.
Thank you for your consideration of my concerns.
Larviciding with Bti
A larvicide (or larvacide) kills larvae.
In a rare too-good-to-be-true moment, the biological agent Bti prevents mosquito larvae from maturing. It’s made from bacteria called Bacillus thuringiensis israelensis, which affects no other forms of life except two other nuisance insects (black flies and midges). It is organic and totally non-toxic.
You can use mosquito dunks in any standing water that you can’t dump out regularly: a small pond (such as the artificial one pictured here; these larvae leave shadows on the bottom) or stagnant stretch of stream in your yard, or a built-in plant soaking area that no longer drains, etc.
For a small surface area, just break up the dunks in pieces. In any case, reapply every month or so to be sure the Bti is still actively working.
Dunks usually come in packs of 6. If you buy more than one at a time at ACE hardware store in East Bradford (720 W Strasburg Rd., just west of West Chester borough, ask for the Don’t Spray Me! discount.
Just to remind you, we oppose the use of pesticide sprays and SPRAYS HAVE NO EFFECT ON LARVAE (or on eggs, or on pupae, the cocoon-like form that larvae go through before emerging as adults).
For detailed information on Bti, see “Best Natural Mosquito Control: Bti” at mosquitoreviews. Use Bti only on your own property or, with permission, on someone else’s property, but not on public property.
Trash cans that keep out water
Who cares if rain water builds up in trash cans? Everyone should, because:
1) In warm weather, the accumulated water provides ideal breeding opportunities for mosquitoes: warm dank stagnant water with lots of organic matter;
2) The can or bag becomes heavier for disposal crews to pick up and the waterlogged trash is more expensive to put in the landfill;
3) If the water is dumped on the ground, or runs out through holes in the bag or container, it can generate mud and mess (think soft drinks, improperly deposited animal waste, bits of pizza filling…) — especially not what one wants children and pets poking around in.
Here’s a trash can model designed to keep out water:
Study links Deltagard active ingredient deltamethrin exposure to fish embryo malformations
We already know that the common yard product Roundup has been associated with multiple cases of Non-Hodgkins Lymphoma. Now, more and more evidence is mounting that deltamethrin, the active ingredient in Deltagard, causes negative effects when animals are exposed to it.
A recent scientific report from Turkey studied the developmental effects on Zebrafish (Danio rerio) when they are exposed to deltamethrin. Survival rate, hatching, and body malformations were determined after deltamethrin exposure.
The study results showed that DM (deltamethrin) cause body malformations, mortality and and delay hatching, survival rate decreased, and apoptosis increased.
Parlak, Department of Aquaculture, May 2018
The figures above show how survival rate decreased with the concentration of deltamethrin, and malformations increased with concentration.
Deltamethrin easily enters waterways through runoff, which is why it is important to know how Deltagard is affecting our ecosystems. This is also why Deltagard instructions say to not spray the product directly on or adjacent to a waterway. But how can we be sure that when Deltagard trucks spray our lawns and streets in the borough, the poison does not run into the storm drains and affect our wildlife? Also, if deltamethrin has such detrimental effects on zebrafish, who’s to say what unknown effects if may have on insects, birds, dogs, and even humans? As always, it’s better to be safe than sorry. Reduce your use of Deltagard on your property, and express to the county that you are concerned about the use of Deltagard throughout the borough.
- Figures from Evaluation of apoptosis, oxidative stress responses, AChE activity and body malformations in zebrafish (Danio rerio) embryos exposed to deltamethrin
Bti for Mosquito Control
Good advice on larviciding from the US EPA. It’s so much easier to get rid of larvae that can’t escape than winged adults that fly where they wish! And right now is the time to dispatch all possible larvae, before numbers start to multiply.
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1. What is Bti?
Bti is a biological or a naturally occurring bacterium found in soils. (Bti is short for Bacillus thuringiensis subspecies israelensis.) It contains spores that produce toxins that specifically target and only affect the larvae of the mosquito, blackfly and fungus gnat. EPA has registered five different strains of Bti found in 48 pesticide products that are approved for use in residential, commercial and agricultural settings primarily for control of mosquito larvae.
2. Does Bti pose health risks to humans?
No. Bti has no toxicity to people and is approved for use for pest control in organic farming operations. It has been well tested by many studies on acute toxicity and pathogenicity (ability to cause disease) for Bacillus thuringiensis including studies specifically on Bti. Based on these studies, EPA has concluded that Bti does not pose a risk to humans.
3. Where has Bti been used for mosquito control?
Bti is used across the United States for mosquito control. Bti is approved for aerial spraying, which has taken place in Massachusetts, Pennsylvania, Maryland and Michigan, among other states. Bti can be sprayed over waterbodies such as ponds, lakes, rivers and streams. Bti is used to kill developing mosquito larvae by being applied to standing water where those larvae are found. Bti can be used around homes in areas and containers where water can collect, such as flower pots, tires, and bird baths. Bti can also be used to treat larger bodies of water like ponds, lakes and irrigation ditches.
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4. Will Bti work to control mosquito larvae?
Yes, Bti has been shown to be effective in reducing mosquito larval populations and could be effective in controlling mosquitos carrying Zika, dengue and chikungunya in places like Puerto Rico and other areas where these diseases have been identified.
5. Are insects becoming resistant to Bti?
No. There is no documented resistance to Bti as a larvicide. A recent study (Tetreau et al. 2013) confirmed previous research showing a lack of Bti resistance in mosquito populations that had been treated for decades with Bti.
6. Are there special precautions to be taken during Bti spraying?
No special precautions are needed for applying Bti. A number of Bti products are sold as “homeowner” products and are easy and safe to use. People do not need to leave areas being treated. However, as is the case with many microbial pesticides, some commercial use Bti products may require applicators to wear a dust/mist filtering mask.
7. How will I know if aerial spraying is going to take place?
Decisions about where and when to spray will be made by local officials. Listen for announcements in your community with the dates, times and locations of upcoming sprayings on social media sites, newspapers or radios.
8. Does Bti pose risk to crops or water supplies?
No. Bti has no toxicity to people, so it can be applied safely to mosquito habitat without a detrimental impact on food crops or water supplies. In fact, Bti can be used for pest control in organic farming operations. It is important to follow the label for any Bti product to ensure that the product is being used correctly. There are multiple Bti products and some are allowed to be used on certain drinking water (e.g., cisterns) while others are not intended for that use.
9. Is Bti harmful to wildlife including honey bees?
Studies indicate Bti has minimal toxicity to honey bees. Bti produces toxins that specifically affect the larvae of only mosquitoes, black flies and fungus gnats. These toxins do not affect other types of insects including honey bees.
10. Is there a medical test to show whether I’ve been exposed to Bti?
Since Bti has no toxicity to humans, a medical test to show exposure to the active ingredient has not been developed.
11. What other measures should be taken to control mosquitoes besides aerial spraying?
Eliminate any standing water (even tiny amounts) to prevent infected mosquitoes from laying their eggs (breeding) in standing water.
Use window and door screens to block infected mosquitoes from entering your home, workplace or children’s schools.
Use EPA-registered insect repellents to prevent getting bitten. EPA-registered means the product works and is safe when you follow the directions.
Dress in light-colored clothing, long pants, and long sleeves and try to avoid areas where mosquitoes are present.
Bill to ban a toxic pesticide needs your support
H. R. 230 has been proposed for the US Congress to ban all use of the pesticide chlorpyrifos. Basically:
10 chlorpyrifos shall be deemed to generally
11 cause unreasonable adverse effects on the environ-
12 ment due in part to dietary risks to humans posed
13 by residues of that pesticide chemical on food;
14 the Administrator of the Environmental
15 Protection Agency shall cancel the registration of all
16 uses of chlorpyrifos…
Download the bill and see the latest info here.
Contact Chester County rep Chrissy Houlahan to ask her to support the bill here.
Although the EPA banned most residential uses of organophosphates like chlorpyrifos in 2001, it has so far been turned back in banning chlorpyrifos in agriculture and mosquito control.
Although Chester County has not been spraying chloripyrifos to try to kill adult mosquitoes, nothing currently prevents it from doing so.
More background here. Also search chlorpyrifos on our site for posts like here.
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