Mosquito Species in eastern Massachusetts

There are 46 mosquito species commonly found in Massachusetts. Each species has it's own unique combination of characteristics. The presence of a particular mosquito species is dependent on the type of nearby wetland or habitat. Examples of different habitats that produce different mosquito species include permanent swamps, temporary woodland pools, river flood plains, cattail swamps or artificial containers. The last item can be almost any container which can hold stagnant water for at least a week in the summer, including roadside highway drains, old rimless tires, unused swimming pools, uncovered empty trash cans, and bird baths. The species of mosquito found at any one time in an area is dependent on temperature and season, as there are early spring, late spring, summer, and mid-summer species. Some mosquito species have several generations each summer, so their populations increase as the summer goes along. Most mosquito species are active primarily during dusk and dawn or during cloudy warm days. However, one local species is active all night and one species will bite during hot sunny days. Three of our local mosquito species will enter protected shelters such as houses, and it is usually one of these three species that annoy people while they are trying to sleep. While some mosquitoes are indiscriminate about what they bite, most are selective. Some of our mosquito species feed primarily on humans and other mammals, while others mostly bite birds, and still others feed on amphibians (such as frogs) or reptiles (such as snakes). Some species are very aggressive and persistent, while others are very shy. Finally, some deliver a more annoying bite that results in more itching. The chance of acquiring a mosquito-borne disease in Massachusetts is extremely rare. However, the species which are believed to transmit Eastern Equine Encephalitis include some of the most numerous species, which on given nights can be caught on any suburban or rural property in eastern Massachusetts. Mosquitoes also transmit animal diseases, and the probability of a pet dog or cat acquiring heartworm is not so remote. It is recommended that a veterinarian give dogs and cats preventative medication.

Aedes abserratus--Very common early spring to early summer mosquito pest of

humans and other mammals. Larvae are found in temporary spring

pools and margins of permanent waters in April. Readily bites

in shaded areas during the day.
Aedes aurifer--Found occasionally in the spring and early summer. Vicious

biting pest of humans and other mammals. Larvae are found in the

spring in open marshes.
Aedes canadensis--Common late spring and summer mosquito. Fierce biting

pest of humans and other mammals. Larvae are abundant in late

spring and found occasionally during the summer in woodland pools,

swamp borders and grassy hummock areas. This long-lived mosquito

is the primary suspect in the transmission of heartworm to dogs

and a possible suspect in the transmission of EEE from birds to

humans.
Aedes cinereus--Common late spring and early summer mosquito pest of

humans and other mammals. Larvae are found in late April and May in

tussock and leather-leaf marshes.
Aedes excrucians--Very common mid spring and early summer mosquito pest of

humans and other mammals. Larvae are found in a wide range of

wetland habitats. This mosquito is a suspect in the transmission of

heartworm to dogs.
Aedes sollicitans--Very common summer mosquito found primarily along the

coast. This aggressive mosquito will bite on a hot sunny day and

is known to fly long distances, so it occasionally turns up in

our district. Larvae are found on the edges of salt marshes.
Aedes triseriatus--Common summer mosquito. A pest of humans and other

mammals. Most of these larvae actually are found in old rimless tires,

although some are found in other shaded artificial containers and in tree holes.
Aedes trivittatus--Common summer mosquito. Larvae are found in floodwater

pools in both swamps and marshes. This pest is a persistent biter,

and will even bite during the day.
Aedes vexans--Very common summer mosquito. This pest of humans and other

mammals can have several generations each season, so the population

may increase during the summer. Larvae are found in a wide variety

of temporary pools and wetlands. This mosquito is a suspect in

the transmission of EEE from birds to humans.
Anopheles punctipennis--Found occasionally in the spring and summer. This

pest of humans and other mammals has a mildly annoying bite. The

larvae are found in a wide variety of wetlands including permanent

swamps and along the edges of ponds and slow moving streams.
Anopheles quadrimaculatus--Common Summer mosquito. A pest of humans and

other mammals that readily enters houses and has a mildly annoying

bite. The population increases during the summer. The larvae are

found in clear water amongst low vegetation or floating debris,

in permanent swamps, and along the edges of ponds and slow moving

streams.
Culex pipiens--Very common year round mosquito which primarily feeds on

birds. It will readily enter a house, but is considered shy. It

will typically only bite people when they are motionless, usually

while they are sleeping. The larvae

are found in artificial containers and in polluted waters.
Culex salinarius--Common summer mosquito. A fierce biting pest of birds,

humans and other mammals which can have several generations in

a summer, so the population may increase during the season. This

mosquito is active all night. Larvae are found in both fresh and

polluted grassy hummock areas of permanent water swamps.
Culiseta melanura--Common spring and summer mosquito. A bird- feeding

mosquito that can have several generations per year, so the population

may increase towards the end of the summer. Larvae are found in

holes in the root structures of white cedar and red maple trees

in swamps. This is an important mosquito species because it is

believed to spread EEE virus through the bird population. This

mosquito does not bite humans.
Coquillettidia perturbans--Very common mid-June to mid-August mosquito. An

indiscriminate pest of birds, humans and other mammals that is

known to be a vicious biter, and will readily enter homes. The

larvae are unusual in that they are found attached to the submerged

roots of cattails and a few other aquatic plants. This trait makes

this species impervious to control using pesticides that are effective

against larvae of other species. This mosquito is suspected in

the transmission of EEE from birds to humans.
Culex restuans, Culex territans, Culiseta morsitans, Uranotaenia sapphirinia-

These are unimportant biters of birds and amphibians that are

found in a variety of wetlands. Ur.sapphirinia are unusual

because under a microscope they are an iridescent green.

Spray Schedules

The East Middlesex Mosquito Control Project will begin its larval control program using the pesticide, Bti, at the beginning of April 2000. Helicopter applications of Bti will take place over specified large wetland areas in mid April. The adult mosquito control program using the pesticide, resmethrin, will begin at the end of May.

Pesticide Information

Adult Mosquito Control Pesticides Adult Mosquito Control Pesticides

Resmethrin

NOTE: EPA toxicity levels are grouped into four categories: (IV) relatively non-toxic, (III) slightly toxic, (II) moderately toxic, and (I) highly toxic. Resmethrin is rated as slightly toxic (III). By comparison, caffeine would be labeled moderately toxic (II).

FACTS ABOUT RESMETHRIN

oResmethrin is a type I pyrethroid
oPyrethroids are synthetic compounds related to the naturally occurring Chrysanthemum sp compound pyrethrum
oType I pyrethroids affect the nervous system by causing sodium channels to remain open longer causing repetitive firing of nerves ("jitters")
oSymptoms of acute poisoning by type I pyrethroids include restlessness, incoordination, and hyperactivity, followed by prostration and paralysis
Toxicity
to people: LOW RISK

found to be a non-irritant to skin & eyes

not found to be a skin sensitizer (allergen)

not found to be oncogenic (tumor-producing)

not found to cause birth defects

rapidly metabolized (broken down by the body)

metabolic products are non-toxic

Toxicity to non-targets:
other mammals - low risk
birds - low risk
fish - high risk

However, (1) resmethrin is unstable and insoluble in water, (2)

breakdown products have low to no toxicity, and (3) no fish kills

have been attributed to proper use of resmethrin.
bees - high risk

However, (1) resmethrin is applied after dusk when bees are not

active, (2) resmethrin is applied at very low rates, and (3) resmethrin

breaks down rapidly in sunlight.
other invertebrates - unknown but probably high, especially to

night-flying insects. Resmethrin is a very good insecticide.

However, it can be rapidly biodegraded (broken down by living

systems).
Environmental Risk

1. resmethrin breaks down rapidly in sunlight

2. resmethrin is unstable and insoluble in water - risk to groundwater

is low

3. resmethrin is non-volatile (doesn't release vapors)

4. resmethrin breakdown products have low to no toxicity
Therefore: ENVIRONMENTAL RISK IS LOW

Efficiency as a Pesticide
1. resmethrin is applied when mosquitoes are flying
2. resmethrin produces rapid knockdown and mortality in mosquitoes at concentrations as low as 3%
resmethrin (applied at a rate of 1/2 oz of soy bean oil mix per acre, 18% of mix is scourge, 18% of scourge is resmethrin & 54% is the synergist piperonyl butoxide)
3. resmethrin is not persistent in the environment, so the
chance of resistance developing is low

Larval Mosquito Control Pesticides

Bti

NOTE: EPA toxicity levels are grouped into four categories: (IV) relatively non-toxic, (III) slightly toxic, (II) moderately toxic, and (I) highly toxic. Bti is rated as relatively non-toxic (IV). By comparison, caffeine would be labeled moderately toxic (II).

FACTS ABOUT BTI

oBti is a microbial insecticide
oBacillus thuringiensis israelensis is a rod-shaped bacterium which releases a toxin crystal when it reproduces
oThis crystal is only toxic to mosquitoes, black fly, and a few related
species
oBti is considered relatively non-toxic to humans and other mammals

Toxicity
to people: LOW RISK

found to be a non-irritant to skin & eyes

not found to be oncogenic (tumor-producing)

not found to cause birth defects

Toxicity to non-targets:

other mammals - essentially no risk

birds - essentially no risk

fish - essentially no risk

bees - essentially no risk

other invertebrates - low to none for most other invertebrates, including other insects. However, Bti
has been found to affect dixids, chironomids, and ceratopogonids.

Environmental Risk
1. Bti is highly specific for mosquito and black fly larvae
2. Bti is applied directly to mosquito-producing habitats
3. Bti produces no toxic residues - risk to groundwater is low
4. Bti is non-volatile (doesn't release vapors)
5. Bti is harmless to beneficial aquatic organisms, including
insect predators
Therefore: ENVIRONMENTAL RISK IS VERY LOW

Efficiency as a Pesticide
1. Bti is applied to larval habitat to kill mosquitoes before
they become pests
2. Bti produces rapid knockdown and mortality in
mosquitoes, usually within 24 hours after application 3. Bti is not persistent in the environment, so the chance of resistance developing is low

Altosid

NOTE: EPA toxicity levels are grouped into four categories: (IV) relatively non-toxic, (III) slightly toxic, (II) moderately toxic, and (I) highly toxic. Altosid is rated as relatively non-toxic (IV). By comparison, caffeine would be labeled moderately toxic (II).

FACTS ABOUT ALTOSID

o Altosid is an insect growth regulator
o the active ingredient, Methoprene, is an insect juvenile hormone mimic
o Insect juvenile hormone affects the development of the insect to its adult stage (metamorphosis)
o Altosid is considered relatively non-toxic to humans and other mammals

Toxicity
to people: LOW RISK

found to be non-irritating to skin & eyes

found to be non-sensitizing to skin

not found to be oncogenic (tumor-producing)

not found to cause birth defects

Toxicity to non-targets:

other mammals - essentially no risk

birds - essentially no risk

amphibians - slight to moderate risk

fish - slight to moderate risk

bees - essentially no risk

other invertebrates - potentially high for other aquatic insects

and some aquatic invertebrates

Environmental Risk
1. Altosid is applied directly to mosquito-producing habitats
2. Altosid produces no toxic residues - risk to groundwater is
low
3. Altosid is non-volatile (doesn't release vapors)
Therefore: ENVIRONMENTAL RISK IS LOW

Efficiency as a Pesticide
1. Altosid is applied to larval habitat to kill mosquitoes
before they become pests
2. Altosid Briquets release effective doses of pesticide for
up to 30 days, providing long term control of mosquitoes

Material Safety Data Sheets (MSDS)
* Resmethrin
* Permethrin
* Bti
* Altosid

Process to Exclude Property From Public Area Wide Pesticide Applications

State Regulation 333 CMR:13:04 provides a method for homeowners to exclude their property from public area wide pesticide applications. The regulation requires that residents send a certified letter to the town or city clerk by March 1st of each year. The certified letter should specify: your name, address, telephone number, the names of all abutters, and the spray program for which the exclusion is requested. In addition the boundaries of the property must be marked every 50' by tin pie plates or other appropriate means. Questions regarding the regulation can be answered by calling the Massachusetts Pesticide Bureau at (617) 727-3000. Questions on pesticide applications by the East Middlesex Mosquito Control Project can be answered by calling (781) 899-5730.

Mosquito control on your own property

What homeowners can do to prevent water-holding containers from becoming breeding sites for mosquitoes.

Mosquitoes are a controllable pest. The mosquitoes bothering you may be emerging from wetlands located up to 2 miles away or they may be coming from containers on your own property. Homeowners should be aware that once a container is inundated with rainwater in the summer, it becomes a likely site for a mosquito to lay eggs on the water surface. If the water remains in the container for more than a week, the larvae that emerge from the eggs will have enough time to develop into their adult flying stage. It is not unusual to see hundreds of mosquito larvae in as little as one pint of water. Once mosquito larvae mature and emerge from the water, their likely targets will be the owners of the yard and their neighbors.

Residents should inspect their own yard and take appropriate steps to prevent containers from becoming a source for mosquitoes. Anywhere water collects and remains stagnant for at least a week is a potential breeding site for mosquitoes. Containers most frequently found to breed mosquitoes are: rimless tires, infrequently used wading pools, water in loose fitting pool covers, uncovered boats, barrels, buckets, pet dishes, bird baths, wheel barrows, and vases containing flowers and plant cuttings,

To prevent a yard from becoming a source for mosquitoes, homeowners should make a thorough inspection of their property and remove or modify water-holding containers that may breed mosquitoes. Tires should either be disposed of or stored inside a garage or cellar. Potential water holding containers such as rubbish barrels, buckets, wheelbarrows and small boats should be covered or stored upside down. The water in wading pools and birdbaths should be changed at least once a week. Infrequently used pools should be tightly covered or chlorinated. Barrels used by gardeners to collect rainwater should be emptied once a week or treated with Bti, an effective and relatively non-toxic mosquito larvicide. Ornamental ponds should be stocked with small fish or treated with Bti as needed. Bti is available to homeowners under the product name, Mosquito Dunks.

If residents have any questions about mosquitoes or how to control them, contact the East Middlesex Mosquito Control Project at (781) 899-5730

Links to Related Sites

- American Mosquito Control Association
- Northeastern Mosquito Control Association
- New Jersey Mosquitoes Biology and Control
- Norfolk County Mosquito Control Project

More Information on Mosquitoes, Biting Flies and Ticks

Eastern Equine Encephalitis (Mass. DPH)
West Nile Encephalitis (CDC)
Aids and Mosquitoes (Rutgers)
Frequently Asked Questions on Mosquitoes (Rutgers)
Mosquito Repellents (Mass. DPH)
Insect Bites and Insect Repellents (Mass. DPH)
Electronic Repellers, Bug Zappers, Citrosa, Bats and Purple Martins (Rutgers)
Lyme Disease (Mass. DPH)
Human Granulocytic Ehrlichiosis (Mass. DPH)
Dog Heartworm (Rutgers)
Black Flies (Ohio State)
Horse Flies and Deer Flies (Ohio State)