Brooklyn Community Gardeners

THE GREAT MOSQUITO HUNT OF 2006

Preliminaries

Annie Fox's Statement on Garden Mosquito Control

As everyone who has been around the garden over the past few years knows, mosquitoes have become a major issue here. Last year, by mid-summer it was impossible to spend ten minutes in the garden at any time of day without getting several bites. It literally drove my son and me to abandon the garden due to his mosquito allergy. It also creates a serious problem for the surrounding neighborhood, and, in light of the West Nile virus, poses larger health risks even for non-allergic people. Additionally, it simply turns the garden from a lovely oasis for community members to someplace they need to hurry past to avoid bites. Fortunately, they are many ways we can safely and dramatically reduce our mosquito population.

Below is an outline of some control measures we can consider. Many thanks to Emily Brown for looking up a large amount of information. If anyone things of additional suggestions or avenues of research after this meeting, please contact me.

I. Physical Control –
a. Source Control – One of the most effective and cheapest means of reducing the mosquito population is eliminating good places for them to lay eggs. While having one of more people patrol the sources listed below would make a big difference, to be truly effective, this really needs to be a community effort. In general, any standing water makes an ideal home for egg and larva, and some species of mosquitoes can go from egg to adult in a matter of days.
i. Water Barrels – Last year, the worst barrel got so infested with larva that the water itself looked alive. All the barrels provide sanctuaries for mosquitoes, though.
1. Possible solutions
a. barrel covers – Either a solid or mesh cover could be purchased or made for each barrel. Then, when not actively in use, members need to make sure the barrels are covered.
i. Even if someone regularly patrols to make sure the barrels are covered, it doesn’t take long for mosquitoes to lay eggs, so we all need to be responsible.
ii. Some barrels have holes cut in the side, so the holes either need to be covered or those barrels could be retired.
b. move barrels from worst locations – Reportedly, one barrel along 15th street was particularly bad last year, and also kept having dog excrement from the street tossed into it. When we have barrels in problematic locations like that, it is simple enough to relocate them. We need to discuss a second best location with anyone who has a plot near a barrel that needs to be moved.
c. water agitation – Stirring up the water and scraping along the top edges 3 times/week would greatly help.
d. vegetable oil – Adding a small amount of vegetable oil to each water barrel after use could form a film that would interfere with larval air supply.
ii. Pond – covered in other sections
iii. Other Standing Water
1. Anything that collects water, including uncovered trashcans, the cats’ water bowl, and improperly stored tools, gives mosquitoes a place to breed.
2. While assigned individuals can patrol these sources, all gardeners also need to help with this around individual and community plots.
3. A cute, friendly reminder sign that people see when leaving the garden may help us all remember to go back and check our work areas for anything that can collect water.
4. Whomever is in charge of feeding the cats needs to be sure to empty and wash the bowls a few times each week.
b. Bug Zappers
i. Generic bug zappers – These do not attract mosquitoes. They may, however, kill some beneficial insects, or neutral ones, which are helpful by attracting mosquito predators.
ii. Specialized mosquito zappers – These use a combination of octenol, carbon dioxide, heat, and light to attract mosquitoes.
1. Advantages
a. Can be very effective.
b. Low effort.
2. Disadvantages
a. Will still kill many non-pest insects. (I consider this a pretty big negative.) For this reason, it is not compatible with bringing in predators of adult mosquitoes.
b. Good ones are very expensive (upwards of $400.00).
c. They need a power source, either large batteries or electric outlets.


II. Biological Control
a. Predators
i. Fish – Fish that prey on the larvae can be very useful in the pond, but we can’t keep them alive in the barrels. I know someone else has been doing the research for the best fish to add in the pond, so I’ll just mention a few considerations.
1. Mosquitofish would terrorize other fish currently living in the pond, so other breeds are preferable.
2. Some species would eat tadpoles, so we need to be careful to make sure all species added to the pond can coexist.
3. Before adding species to the pond, we need to run water quality tests and make any necessary adjustments, and consider its overall carrying capacity given its size.
ii. Frogs & Toads
1. Advantages
a. Some aquatic frogs and toads do a wonderful job of keeping mosquito eggs in check.
b. They would add to the overall biological diversity and educational value of the garden.
c. Relatively inexpensive.
2. Disadvantages
a. We need to make sure tadpoles won’t just get eaten by fish.
3. Other considerations
a. We need to make sure we get native species. I found a source to purchase the native tadpole species, or we can collect eggs ourselves in Prospect Park.
b. The species should be compatible with the fish population.
4. Before adding species to the pond, we need to run water quality tests and make any necessary adjustments, and consider its overall carrying capacity given its size.
iii. Bats – A single brown bat can consume up to 500 mosquitoes an hour!
1. Attracting Bats
a. Bat house – The single best way to attack bats is to add a bat house. I found one we can order for $40, or we may be able to build one for less.
i. It needs to be placed at least 10 feet above the ground.
ii. It needs to be in a location that gets plenty of sun.
b. It helps to also make sure we have a healthy moth population since bats love to eat moths.
c. There is already a good population in Prospect Park, so it should be relatively easy to attract them from so close.
2. Advantages
a. They are very efficient at controlling mosquitoes.
b. Once we have the bat house in place, there are no maintenance costs.
c. They would add to the overall biological diversity and educational value of the garden.
3. Disadvantages
a. It may take up to a year to attract the bats, but, since there is a population close by, they will probably come sooner.
b. Bacterial Control - Bacillus thuringiensis (Bt) is a natural disease of larvae. The israelensis variety infects mosquitoes and a couple other pest insects. This is a microbial pesticide.
i. Advantages
1. It is cheap.
2. It is easy to use since we just would add it to standing water sources like the pond and perhaps the barrels.
3. It is relatively effective.
ii. Disadvantages
1. Reports of its effectiveness vary.
2. While generally safe for humans, other mammals, and fish, it has been shown to be a mild eye and skin irritant.
3. Some wetlands where it has been used experienced an overall decrease in biological diversity, which may mean it has broader effects than we know.
III. Chemical Control – My general feeling is that we want to avoid going this route for health and environmental reasons, but I will explore it further if requested.

From: "Annie Fox"
To:
Subject: Re: mosquito update?
Date: Tuesday, May 30, 2006 6:08 AM

I'm sorry I couldn't find time to write more or
sooner. My schedule is still a mess, which means my
head is in a fog.

Briefly:

Mosquito Control

We have hit the time of year when mosquitos are
starting to appear, so it is important that everyone
chip in to make sure they can't breed in the garden.
We have mosquito dunks in the pond, which means they
can't breed in there. The only water barrels in use
have lids, so we all need to remember to replace the
lids after using the water. Also, everyone needs to
make sure to store buckets and tools so they can't
collect water. I am trying to stir up the barrels and
scrape the sides every few days, as well as dump out
water collecting in obvious places. By being
diligent, I'm sure we will have a much more pleasant
season than in previous years.

The representatives of the BQLT who heard our thoughts
on putting up a bathouse like the idea, and we may
become a pilot project for area community gardens.
Since we have already missed the window for getting
them to roost this year, I hope to have the bat house
up and ready for them by the end of summer, so it will
be ready for next season. However, we can still try
to attract bats to the garden to feed, since some live
as close as Prospect Park. The best way to do this is
to plant fragrant night blooming flowers because they
are favored by moths. Bats love moths, and if they
come to eat them, they will also gobble up mosquitos.

From: "Jessica Katz"
To: "6/15 Green"
Cc: "Patrick McCarty"
Subject: some cool sites for more info about bats and bat houses
Date: Friday, May 26, 2006 5:41 AM

Howdy,

I got curious and cruised around the internet for more info/options on bat plans, life cycle, how to attract them, etc. Apparently there are about nine species of bats found in New York. The most common is the "little brown bat".

Here are some really good sites for more info:


http://www.batcon.org/home/default.asp (Bat Conservation International)


http://www.nwf.org/backyardwildlifehabitat/bathouse.cfm (National Wildlife Federation)

http://www.50birds.com/bats.htm

http://www.batcon.org/bhra/economyhouse.html

http://www.b4ubuild.com/plans/bat_houses.shtml

http://www.dnr.state.wi.us/ORG/LAND/er/publications/bats/assembly.htm
.

Jessica Katz
Executive Director
The Brooklyn Queens Land Trust
c/o Trust for Public Land
666 Broadway, 9th Floor
New York, NY 10012
Tel: 212-677-7171 x 643
Fax: 212-353-2052
Email: jikatz@mac.com

“Thank you for your e-mail inquiry that has been forwarded to us at the Gardener's Resource Center by our Webmaster. The best solution to your difficulty would be water/rain barrels with a tight fitting lid (and a community conscientious enough to keep the lids on). These are available online. A Google search, "rain barrels," will give you lots of options. Another, cheaper solution, but perhaps controversial in its own way, is a product called "Mosquito Dunk." This is a donut shaped insecticide that floats on the surface of water barrels and kills mosquito larva. The water in which the dunk sits is said to be safe for vegetables and plants. For a discussion about this product, and a source, go to the National Gardening Association website:
http://www.garden.org/search?keyword=mosquito+dunk&q=search
We are sending you by regular mail a leaflet about the Gardener's Resource Center and a brochure describing the many benefits of membership in the Brooklyn Botanic Garden. This information service for gardeners and the Garden's other important programs are made possible in part by the generosity of our members. To find out more about the Garden, please visit our website at http://www.bbg.org/mem/index.html.”

I have a copy of the brochure, and would be happy to make copies available to any garden member interested. If you have a fax number, that’s the easiest way for me to get it to you, but I can also put a few copies in the plastic holder on the kiosk at the garden for anyone that’s interested.
Additional material on mosquito control can be found by following these links:

http://www.gardensalive.com/article.asp?ai=460
http://www.purplemartin.org/
http://www.purplemartin.org/main/letter.html
http://www.gardensalive.com/article.asp?ai=572
http://www.gardensalive.com/article.asp?ai=751
www.dirtdoctor.com

This comment was sent to me via e-mail:
“There are also mosquito rings that you can buy at an ornamental pond outlet. These are OK for fish. Fish are very sensitive so I do not think that the material they contain is bad for us. Also remember that mosquito need only the equivalent of a half a cup of water, so your problem might not be the rain barrels only. My best, Cordalie Benoit”

Annie is apparently interested in putting the batbox on a 10’ – 15’ pole, hopefully on the sunny side of the garden. Does anyone want to help out with that? Does anyone know how deep it should be sunk into the ground to ensure stability (especially if/when the ground near it is soft from rain or watering? We don’t want to have it tip over and bean someone on the head – not good community relations, and I think it would be a huge insurance no-no. She suggested putting cement or concrete around the base of the pole for additional stability. Any feedback on this would be helpful.

More solid & integrated information from various sources

How fast can mosquitoes fly?
Depending upon the species, mosquitoes can fly at about 1 to 1.5 miles per hour.

How far can mosquitoes fly?
Mosquito species preferring to breed around the house, like the Asian Tiger Mosquito, have limited flight ranges of about 300 feet. Most species have flight ranges of 1-3 miles. Certain large pool breeders in the Midwest are often found up to 7 miles from known breeding spots. The undisputed champions, though, are the saltmarsh breeders - having been known to migrate up to 100 miles in exceptional circumstances, although 20 to 40 miles are much more common when hosts are scarce. When caught up in updrafts that direct them into winds high above the ground, mosquitoes can be carried great distances.


How much do they weigh?
Smaller species found around houses commonly weigh about 2.5 milligrams. Our largest species weigh in at a whopping 10 milligrams.


How much blood does a mosquito take in a meal?
When feeding to repletion, mosquitoes imbibe anywhere from 0.001 to 0.01 milliliter.

Why do mosquitoes feed on blood?
Female mosquitoes imbibe blood so that their eggs can mature prior to laying. It serves no nourishment function. Males do not take blood meals at all. In order to obtain energy, both male and female mosquitoes feed upon plant nectars - much in the same manner as honeybees.

What good do mosquitoes do?
Mosquitoes fill a variety of niches which nature provides. As such, placing a value on their existence is generally inappropriate. Although the fossil record is incomplete, they have been known from the Cretaceous Period (about 100 million years ago) in North America. Their adaptability has made them extraordinarily successful, with upwards of 2,700 species worldwide. Mosquitoes serve as food sources for a variety of organisms but are not crucial to any predator species.

How long do mosquitoes live?
Lifespan vary by species. Most adult female mosquitoes live 2-3 weeks. Some species that over-winter in garages, culverts and attics can live as long as 6 months.


If mosquitoes were eradicated, how would this affect the ecosystem?
Given that Nature abhors a vacuum, other species will fill the niches vacated by the mosquitoes after an initial shuffling period of variable length. Be advised, though, that species replacing mosquitoes may be even worse - it's extremely difficult to predict. Mosquitoes' ability to adapt to changing environments would make them all but impossible to eradicate.


How high do mosquitoes fly?
In general, mosquitoes that bite humans prefer to fly at heights of less than 25 ft. Asian Tiger Mosquitoes have been found breeding in treeholes over 40 feet above ground. In Singapore, they have been found in apartments 21 stories above ground. Mosquitoes have been found breeding up to 8,000 feet in the Himalayas and 2000 feet underground in mines in India.

Can mosquitoes transmit AIDS?
Many studies have been conducted on this issue in the United States and abroad. To my knowledge, there has never been a successful transfer of the virus from an infected source to another host by bloodfeeding insects under experimental conditions. The experts have concluded that the insects are not capable of such transmission. Many biological reasons would lead one to this same conclusion, but the extensive experimental studies are the most powerful evidence for the conclusion.

HIV DOES NOT replicate in mosquitoes. Thus, mosquitoes cannot be a biological vector as they are for malaria, yellow fever, or dengue. In fact, mosquitoes digest the virus that causes AIDS.
There is no possibility of mechanical transmission (i.e., flying contaminated syringes); even though we all know that HIV can be transmitted by dirty needles. However, the amount of "blood" on a mosquitoes' mouth parts is tiny compared to what is found on a "dirty" needle. Thus, the risk is proportionally smaller. Calculations based on the mechanical transmission of anthrax and Rift Valley fever virus, both of which produce very high titers in blood, unlike HIV, showed that it would take about 10,000,000 mosquitoes that first fed on a person with AIDS and then continued feeding on a susceptible person to get 1 transmission.
Mosquitoes are not flying hypodermic needles. Mosquitoes regurgitate saliva into the bite wound (the normal route for disease transmission) through a separate tube from that through which it imbibes blood.

Which mosquitoes transmit WNV?
At least 43 species of mosquitoes have been found infected with the West Nile virus in the United States. Not all of these, however, are capable of maintaining the virus in such a manner as to permit them to transmit it among organisms. Many of these infected mosquitoes feed only upon birds, thus contributing to a cycling of the virus among avian populations. Other species feed upon these infective birds and then will feed upon mammals, including humans. These are called "bridge vectors" because they serve as a conduit for the virus to travel from its reservoir in birds to its final host in humans or other mammals. In urban settings, Culex pipiens is usually the primary vector. In rural areas, particularly in the western part of the United States, Culex tarsalis is the primary transmitter. As control measures for each of these mosquitoes are considerably different, it's important to know which is known to be in your area. Contact your local mosquito abatement district or the Technical Advisor of the American Mosquito Control Association (904-215-3008) for information regarding the mosquitoes found in your area.


Which state has the fewest mosquitoes?
West Virginia has the fewest species (26), while Texas has the most species (85). A determination of absolute numbers of mosquitoes for each state is extremely difficult, however, as mosquito populations tend to be focal, depending upon amount of breeding habitat, potential hosts and climatological factors - regardless of the number of species. Thus, relatively dry places like Nevada, Arizona and New Mexico may have intense mosquito activity in areas where water is present. Alaska has a relatively short season, but biting activity during that time is prodigious, indeed. Mosquitoes are particularly prolific in areas with rice farming, extensive salt marsh or dredge spoil.


What attracts mosquitoes to me?
Why some people seem to be more attractive than others to mosquitoes is the subject of much repellent (and attractant for traps) research being conducted nationwide. Carbon dioxide is the most universally recognized mosquito attractant and draws mosquitoes from up to 35 meters. When female mosquitoes sense carbon dioxide they usually adopt a zigzagging flight path within the plume to locate its source. Once in the general vicinity of a potential host, other cues predominate, including body odors (sweat, lactic acid, etc.) and heat. Odors produced by skin microflora also play a part in inducing the mosquito to land. Over 350 compounds have been isolated from odors produced by human skin. Either singly or in combination, many of these compounds may be attractants - and many may be repellents. As you can see, the situation is complicated and will require many years of testing before it can be sorted out. Visual stimuli, such as movement, also factor into host-seeking. What can be safely stated, though, is that ingestion of garlic, vitamin B12 and other systemics has been proven in controlled laboratory studies to have no impact on mosquito biting. Conversely, eating bananas did not attract mosquitoes as the myth suggests, but wearing perfumes does. People drinking beer have been shown to be more attractive to mosquitoes. Limburger cheese has also been found to be attractive. Scientists have theorized that this may explain the attractancy some mosquitoes find for human feet.

Which repellent works best?
N,N-diethyl-3-methylbenzamide (DEET) remains the standard by which all other repellents are judged. DEET was developed by the U.S. Department of Agriculture and was registered for use by the general public in 1957. It is effective against mosquitoes, biting flies, chiggers, fleas, and ticks. Over 25 years of empirical testing of more than 20,000 other compounds has not resulted in another marketed chemical product with the duration of protection and broad-spectrum effectiveness of DEET. Most apparent repellency failures with DEET are due to misapplications, so care should be taken to apply it thoroughly (avoiding the eyes and mucous membranes) and to reapply when necessarily. This is crucial to maintain the DEET vapor barrier above the skin. New polymerized 30% DEET cream formulations provide excellent protection not significantly exceeded by higher DEET concentrations. Physicians recommend that a formulation of no more than 10% DEET be used on children. I don't want to use DEET, what else is available? There are a number of EPA-registered alternatives available utilizing lemon/eucalyptus (RepelR) and picaridin (Cutter AdvancedR) formulations. If applied properly and reapplied as needed, they are every bit as effective as DEET, and will provide adequate relief. What larvicides can the consumer purchase and use? There are a few larvicides available for the homeowner to use should source reduction be inadvisable.

"Mosquito Dunks" - These are donut-shaped cakes consisting of Bacillus thuringiensis israeliensis (Bti), a bacterial spore that produces a toxin specific to mosquito and blackfly larvae when ingested. It's essentially non-toxic to non-target organisms. The only downside is that it must be ingested by mosquito larvae, so it's best used where there are little competing food sources - relatively clean water. It's available at Home Depot and most hardware stores.
"Pre-Strike" - Available in both a tablet (Mosquito Torpedo®) and a shaker can. This insecticide mimics the hormones required by insects for metamorphosis. In effect, this product keeps them from becoming adults - problem solved. This product is also non-toxic for all intents and purposes and is available through home and garden centers.
"Agnique MMF" - Available in 1 quart squirt bottle. This is an alcohol derivative that reduces surface tension in the water, preventing the mosquito larvae and pupae from attaching their breathing apparatus, causing drowning. This product is the easiest of the three to use. A squirt at one edge of the wetland would suffice, as the product will sheet across the surface on its own, obviating the need to uniformly apply the product, as is required with the other 2 products. This is also the only larvicide that is labeled for use in potable water, so it's extremely safe. It can presently be purchased over the web from www.e-adapco.com, but should be available at Home Depots and hardware stores sometime in July.

How do mosquitoes get into my house?
Mosquitoes are singularly adept at entering houses through any portal available, be it through broken window or door screens, attic soffits or through bathroom exhaust vents. A favorite resting spot is the garage, so take care to keep resting female mosquitoes from coming into the house through the garage.

What can homeowners do to reduce mosquito bites?
If possible, schedule your activities to avoid the times when mosquitoes are most active - usually dawn and dusk. You should also dress in light, loose-fitting clothing. If you have a deck, light it using General Electric yellow "Bug Lights". These lights are not repellant, per se, but do not attract mosquitoes like other incandescent lights. Mosquitoes are relatively weak fliers, so placing a large fan on your deck can provide a low-tech solution. Citronella candles have a mild repellent effect, but do not offer significantly more protection than other candles producing smoke.


Are backyard misting systems effective?
Scheduled sprays used by these misters may needlessly broadcast pesticides into the environment, affecting mosquitoes and non-target insects alike. Modern mosquito control strategies emphasize an integrated approach, based upon a profound knowledge of the target, so that's its various vulnerabilities can be exploited by the many tools we've developed for that purpose. Effective mosquito control requires continual survey of adult mosquito densities to determine if certain triggers for control are met. This reduces the use of adulticides to only those times when they are required.


Do Bug-Zappers Work?
Black light insect electrocution devices (Bug Zappers, etc.) are purchased in huge quantities by homeowners due to their demonstrated ability to attract and kill thousands of insects over a 24 hr. period. One industry representative estimates that over 1.75 million of these devices are purchased annually in the U.S. But do they really control pest insects? Bug zappers do indeed kill some mosquitoes. However, the only two controlled studies conducted to date by independent investigators at the University of Notre Dame showed that mosquitoes comprised merely 4.1% and 6.4% respectively of the daily catch over an entire season. Even more important was the finding in both studies that there was no significant difference in the number of mosquitoes found in yards with or without bug zappers. What is particularly disconcerting, however, is the number of non-pest insects that comprise the vast majority of trap catch. Many of these insects are beneficial predators on other insect pests. They in turn constitute a major part of the diet of many songbirds. Indeed, reduced numbers of moth and beetle prey species have contributed significantly to the decline of songbird populations in many affluent suburbs. Insect electrocution devices undoubtedly bear some responsibility for this phenomenon. Mosquitoes continue to be more attracted to humans than to the devices. One study conducted in homeowners' backyards showed that of the insects killed by these devices, only 0.13% were female mosquitoes. An estimated 71 billion to 350 billion beneficial insects may be killed annually in the United States by these electrocuting devices.


Do Ultrasonic devices work?
At least 10 studies in the past 15 years have unanimously denounced ultrasonic devices as having no repellency value whatsoever. Yet, consumers flock in droves to hardware stores to purchase these contraptions. Why? The discovery that mosquitoes locate mates in mating swarms via wing beat frequency generated a great deal of research into ultrasound as a potential source of environmentally-friendly control. Yet, all attempts to affect mosquito behavior by ultrasound have fizzled, despite enormous amounts of money spent upon research and development. To be sure, the clever, high-tech, and imperceptible (by humans) use of ultrasound proved to be an exceedingly effective marketing tool for the repeller manufacturers. Homeowners were urged to buy ultrasonic repellers and the like to rid their houses of pests without the need to inhale "even one breath of poisonous spray". This appeal to the public's chemophobia, while extremely effective in diverting attention away from proven preventive and control measures (and toward their repeller products), has undermined an unbiased review of the subject by consumers desperate for a clean, effective, nonchemical means of mosquito control. Unfortunately, no such miracle cure exists. A pioneering study testing five different ultrasonic devices against four mosquito species convincingly demonstrated that ultrasound in the 20-70 kHz range used by these devices had no effect on reorienting flight by female mosquitoes either toward or away from human subjects. Additional tests have shown that sound generators capable of a wide range of frequencies were also ineffective in repelling mosquitoes. The fact is that these devices just do not work - marketing claims to the contrary.


Do mosquito traps work?
An enormous amount of consumer interest has been generated by the marketing of new devices designed to attract, then either trap or kill, mosquitoes. The general idea is to reduce the number of questing mosquitoes that would otherwise be afflicting the homeowner. Many products even claim to significantly reduce or even collapse local mosquito populations by decreasing the number of egg-laying females through their capture. All of these traps utilize some form of attractant that lures the host-seeking female mosquitoes to a capture or killing device. In some cases, mosquitoes are captured via an impellor fan that suctions them into a net, where they desiccate while other trapping systems use a sticky surface to which the mosquitoes adhere when they land. Still others utilize an electric grid to electrocute mosquitoes drawn into contact. These are not set-and-forget devices. Each requires some level of maintenance, i.e. propane tanks need replacement, capture nets need emptying, adhesive boards require replacement and grids require cleaning to ensure their continued effectiveness, particularly in areas of high catch. The process of a mosquito questing for a blood meal involves a complex, interconnected cascade of behaviors, each probably having its own cues, be they visual, thermal, or olfactory. The complexity of these questing behaviors may account for the bewildering variations in trapping efficiency noted for certain species of mosquitoes at different times, seasons and places. With 174 species of mosquitoes currently recognized in the United States, this is no small issue and will require many years before research can provide a clarification. There is some anecdotal evidence that these baited traps, indeed, capture more females of some species than others, depending, to some extent, on the concentration of carbon dioxide emitted and the mosquito species present. There may also be seasonal and circadian variables that affect mosquito responses to certain attractants. Nonetheless, these devices will trap and kill measurable numbers of mosquitoes. Whether this will produce a noticeable reduction in the mosquito population in each case will depend upon a number of factors, e.g. individual tolerance level, absolute mosquito population size, proximity, size and type of breeding habitat producing re-infestation, wind velocity and direction, and species of mosquito present, and others. Thus, the homeowner must still use repellents and practice source reduction methods as adjuncts to realize any measure of relief. Please be cautioned against putting too much faith in traps as your sole means of control. These traps represent an evolving technology that is a most welcome addition to our mosquito control armamentarium. Their potential is great, but shouldn't be overestimated. It's highly unlikely that these devices, whatever their improvements, will ever fully supplant organized community-wide mosquito control programs, for there is no single silver bullet that will prove to be the ultimate answer to mosquito problems.


Do bats serve as an effective mosquito control?
Recently the public has shown increased interest in the value of insectivorous species of bats in controlling mosquitoes. Although untested lately, this is not a new idea. During the 1920's several bat towers were constructed near San Antonio, Texas, in order to help control malarial mosquitoes. Mosquito populations were not affected and the project was discontinued. Bats in temperate areas of the world are almost exclusively insectivorous. Food items identified in their diet are primarily beetles, wasps, and moths. Mosquitoes have comprised less than 1% of gut contents of wild caught bats in all studies to date. Bats tend to be opportunistic feeders. They do not appear to specialize on particular types of insects, but will feed on whatever food source presents itself. Large, concentrated populations of mosquitoes could provide adequate nutrition in the absence of alternative food. However, a moth provides much more nutritional value per capture than a mosquito. M.D. Tuttle, a world authority on bats, is often quoted for his anecdotal report that bats effectively controlled mosquito populations at a popular resort in New York State. While there is no doubt that bats have probably played a visible, if not prominent, role in reducing the mosquito problems in many areas, the natural abatement of mosquito populations is an extremely complex process to study, comprising poorly known ecological relationships. Tuttle attempts to underscore the bats role by citing an experiment in which bats released into a laboratory room filled with mosquitoes caught up to 10 mosquitoes per minute. He extrapolated this value to 600 mosquitoes per hour. Thus, a colony of 500 bats could consume over a quarter of a million mosquitoes per hour. Impressive numbers indeed, but singularly unrealistic when based upon a study where bats were confined in a room with mosquitoes as their only food source. There is no question that bats eat mosquitoes, but to utilize them as the sole measure of control would be folly indeed, particularly considering the capacity of both mosquitoes and bats to transmit diseases.


Do Purple Martins help reduce mosquitoes?
It has been known for many years that bird species like purple martins consume large numbers of flying insects. Proponents of their use in mosquito control are quick to cite J. L. Wade, an amateur ornithologist, who reasoned that an average 4 oz. adult purple martin, due to its rapid metabolism, would have to consume its body weight (14,000 mosquitoes) per day in order to survive. Wade recognized that the purple martins diet includes many other types of insects, but this appears to have been lost on many individuals searching for a natural means of control. In fact, during daylight, purple martins often feed voraciously upon dragonflies, known predators of mosquitoes. At night, when mosquitoes are most active, purple martins tend to feed at treetop level, well above most mosquito flight paths. Ornithologist James Hill, founder of the Purple Martin Conservation Association (PMCA), writes, "The number of mosquitoes that martins eat is extremely insignificant, and they certainly don't control them. In-depth studies have shown that mosquitoes comprise no more than 0 to 3 percent of the diet of martins". They eat only flying insects, which they catch in flight. Their diet is diverse, including dragonflies, damselflies, flies, midges, mayflies, stinkbugs, leafhoppers, Japanese beetles, June bugs, butterflies, moths, grasshoppers, cicadas, bees, wasps, flying ants, and ballooning spiders. Martins are not, however, prodigious consumers of mosquitoes as is so often claimed by companies that manufacture martin housing. An intensive 3-year diet study conducted at PMCA headquarters in Edinboro, PA, failed to find a single mosquito among the 350 diet samples collected from parent martins bringing beakfuls of insects to their young. The samples were collected from martins during all hours of the day, all season long, and in numerous habitats, including mosquito-infested ones. Purple Martins and freshwater mosquitoes rarely ever cross paths. Martins are daytime feeders, and feed high in the sky; mosquitoes, on the other hand, stay low in damp places during daylight hours, or only come out at night. Since Purple Martins feed only on flying insects, they are extremely vulnerable to starvation during extended periods of cool and/or rainy weather. Rather than erecting martin houses to specifically attract insect-eating birds for mosquito control, we should at least promote them for their aesthetic and educational value.


How do mosquito control districts control mosquitoes?
The integrated mosquito management methods currently employed by organized control districts and endorsed by the CDC and EPA are comprehensive and specifically tailored to safely counter each stage of the mosquito life cycle. Larval control through water management and source reduction, where compatible with other land management uses, is a prudent pest management alternative - as is use of the environmentally friendly EPA-approved larvicides currently available. When source elimination or larval control measures are clearly inadequate, or in the case of imminent disease, the EPA and CDC have emphasized in a published joint statement the need for considered application of adulticides by certified applicators trained in the special handling characteristics of these products.

A successful mosquito management program should include the following elements:

larval and adult mosquito sampling;
source reduction;
biological control using native or introduced predators and parasites of mosquitoes,
larviciding and adulticiding, when indicated by surveillance;
resistance monitoring;
disease surveillance in mosquitoes, birds, horses and humans, and
public education.

Are pesticides used in mosquito control safe?
Since its inception, the Environmental Protection Agency (EPA) has regulated mosquito control through enforcement of standards instituted by the Federal Insecticide, Fungicide, and Rodenticide Act. This legislation mandated documentation of extensive testing for public health insecticides according to EPA guidelines prior to their registration and use. These data requirements are among the most stringent in the federal government and are met through research by established scientists in federal, state and private institutions. This process costs a registrant several million dollars per product, but ensures that the public health insecticides available for mosquito control do not represent health or environmental risks when used as directed. Indeed, the five or six adulticides currently available are the selected survivors of literally hundreds of products developed for these uses over the years. The dosages at which these products are legally dispensed are at least 100-fold less than the point at which public health and environmental safety merit consideration. In point of fact, literature posted on the websites of the EPA Office of Pesticide Programs, Centers for Disease Control and Prevention (CDC), American Association of Pesticide Safety Educators and National Pesticide Information Center emphasizes that proper use of mosquitocides by established mosquito control agencies does not put the general public or the environment at unreasonable risk from runoff, leaching or drift when used according to label specifications. (For the federal government's position on risks associated with mosquito control insecticides, visit http:/www.epa.gov/pesticides).

The safety profiles of public health insecticides are undergoing increasing scrutiny because of concerns with how the specialized application technology and product selection protect the exposed public and environment. In fact, well over 200 peer-reviewed scientific studies in various national and international refereed journals since 1980 have documented the safety and efficacy of these public health insecticides at label rates in addition to their application techniques.

How do mosquito districts avoid spraying chemically-sensitive persons?
Organized mosquito control agencies often go to extraordinary lengths to accommodate individuals who, for varying reasons, prefer their property not be sprayed with approved public health insecticides. When surveys indicate the need for adult sprays, they are approved, planned and conducted with special regard to the concerns of chemically sensitive persons. Personal notification of chemically-sensitive individuals of spray times in addition to using Global Positioning Systems (GPS)/Global Information Systems (GIS) technology to reduce the likelihood of drift over unauthorized areas are but a few of the means utilized to ensure mosquito control serves the entire public spectrum. Should you desire that your property not be sprayed, please notify your local district.


Do mosquito sprays affect animals other than mosquitoes?
The extremely small droplet aerosols utilized in adult mosquito control are designed to impact primarily on adult mosquitoes that are on the wing at the time of the application. Degradation of these small droplets is rapid, leaving little or no residue in the target area at ground level. These special considerations are major factors that favor the use of very low application rates for these products, generally less then 4 grams active ingredient per acre, and are instrumental in minimizing adverse impacts.


***If you have other questions, please contact the AMCA Technical Advisor, Joe Conlon, at (904) 215-3008 or amcata@bellsouth.net.

The American Mosquito Control Association, founded in 1935, is a scientific/educational, not-for-profit public service association operating under the corporation laws of the state of New Jersey. It is world-wide in scope, with members or subscribers to its publications in over 50 countries. The majority of its members are in the United States. Under its bylaws, only individuals can be "regular" members, and much of its activity is performed by volunteers, approximately 150 of these serving on Committees. It is an "open" association and anyone may join. The Board of Directors is composed of six officers, nine regional directors and an industry director, all elected by the membership.

And finally... by the end of September...

The mosquito population DID seem to be smaller and less virulent this summer, for a change. And on the evening of Monday, September 25, Annie Fox, my son and I saw a little brown bat wheeling around in the sky around the edges of the garden; he looked like he was feeding. We hope he finds his way INTO the garden and brings his buddies, too. Maybe next year we'll have a bat house in place. See the PDF on building bat houses. Our big issue now is where to put a pole to hold the house...

Emily Brown

Email us
emilyholiday@gmail.com

Mosquitoes and Bats and other flying things, oh my!

Bat Conservation International
National Wildlife Federation
50 Birds
Bat Conservation International - building a bat house
more on bat houses
more on bats
Gardens Alive
Purple Martins
Dirt Doctor
Brooklyn Botanic Garden