[Mosquito Suppliment] Massive Swarms of Midges

Some shore-side communities can be plagued by massive swarms of adult midges. Sometimes called "blind mosquitoes" or "chizzywinks," midges are nonbiting insects in the fly family Chironomidae that breed in natural and constructed bodies of water (such as retention ponds). The worm-like larvae of midges live in lakes, streams, ponds, drainage ditches, brackish water and even in polluted wastewater channels. Most species feed on algae, and are in turn fed upon by fish and other aquatic animals. They sometimes build up to phenomenal numbers. Researchers have reported more than 40,000 larvae per square meter in a central Florida lake and 20,000 larvae per square meter in southern California "water-spreading basins"! Midges are strongly associated with polluted water.

Adult midges can swarm up to a quarter mile from where they lived as larvae. During the day, swarms of midges congregate in cool, shady spots, staining building walls and other surfaces with their droppings. In early evening, outdoor activities at lake-front properties can be almost impossible because midges get into the residents’ hair, ears and eyes. Sometimes, swarms are so dense that you cannot breathe without inhaling midges. Bright lights, particularly security lights shining onto outside walls, bring swarms of midges onto buildings, and midges find their way inside as if by magic.

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Public Health Pests:
UNIQUE Business Opportunities

Public health pests create unique business opportunities for pest management professionals throughout the United States. When the media focuses its attention on a particular vector-driven threat to public health, PMPs can create entirely new service classes within their operations. Although the potential for new revenue sources is attractive — especially in challenging economic times like today — the marketing and messages conveyed demand special attention.

The seasonal outbreaks of mosquito-borne disease raise the public awareness of professional control services. Many companies have programs that incorporate larvacide treatment, inspection and mechanical means, and adulticide applications through handheld ULV units and automated misting systems. Advertising messages for these services need to avoid direct implication of disease prevention or protection. Stating that a PMP program "protects your family against West Nile virus" may violate state pest control laws and regulations (many states vigorously pursue "false and misleading advertising" claims) and invites legal action in the unfortunate event that a customer contracts the disease.

Defending your company in court is expensive, time consuming and detrimental to your insurance loss experience. Although the plaintiff has the burden of proof to demonstrate your company is directly liable for their infection, many juries will be sympathetic to them and many insurance companies will be willing to settle the case, compounding your business costs upon general liability insurance renewal.

Service contracts for mosquito control, including misting systems, need to avoid disease prevention claims and provide a disclaimer for "chemically sensitive" individuals. Before installing automated systems, check with your state’s registry for the locations of these persons if such a list exists. — By Allen Fugler, executive vice president of the Florida Pest Management Association (www.flpma.org)

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Insecticides are not usually a practical solution for large midge outbreaks for these reasons: (1) potential environmental impacts from insecticides applied into water systems, (2) the phenomenal numbers of midges emerging every night, (3) widespread midge breeding areas, and (4) the critical control point may be at the bottom of a lake or other large body of water. (Details on chemical control of midges can be found at www.techletter.com and searching "midges.")

There are other options to reduce midge problems. What follows is a menu of control options to consider and investigate further if you face a problem with massive swarms of midges. Note: Some of these options are reasonable but untested, community-based, expensive or require long-term commitments.

Light Management. Shield or move outdoor lights away from docks, doorways, pools, patios and areas where people gather. Reduce the power of lights in critical areas. Direct the beam to shine only where needed. Avoid shining bright lights on light-colored walls. Sodium vapor lights and dichrom yellow bulbs are somewhat less attractive to midges, as are lower wattage bulbs. Leave lights off until at least an hour after sunset to avoid the period of greatest midge activity. At night, close inside curtains or blinds that face breeding areas.

Screens and Buffers. Trees and other screening vegetation, high walls and other barriers installed between the breeding site and the area at risk can work in a number of ways to reduce midge problems. They can act as a barrier to block the light coming from houses, parking lots, etc., that attracts the midges. They also can intercept wind-blown midges before they reach critical areas. And trees and other buffers can become habitats for midge predators such as spiders.

Decoy Lights. High-intensity lights can be installed to attract midges to noncritical areas and away from critical areas. The lights are typically installed at the water’s edge or even over the water.

Traps. Insect light traps (ILTs) installed between the breeding site and the area at risk (but not too close!) will intercept and kill large numbers of midges and may reduce the number of midges reaching homes and other critical areas. Whether or not the reduction would be significant is unclear. Japanese researchers added the buzz of female wing beats in order to attract male midges and greatly increased ILT catches (more than 90 percent of midges in a swarm are males).

Ecosystem Management. Conditions in the body of water determine the midge population. Altering these conditions can reduce midge outbreaks in some instances but tend to be expensive, hard to implement, and subject to state and federal water regulations. Methods include:

• Improving water quality. Many midge problems are associated with algal blooms caused by pollutants and nutrients getting into the water from food plants, sewage treatment plants, fertilizer runoff and the like. Reducing these pollutants and runoff of nutrients into water can reduce midge problems over the long term.
• Improving water circulation. Poor water circulation causes low oxygen levels and traps nutrients that favor algal blooms and high midge populations. Owners can correct dead spots in water bodies through dredging, thinning aquatic vegetation and altering shorelines. Adding fountains in dead zones will oxygenate water and reduce algal blooms.
• Stocking natural fish predators. Some bodies of water have few predators of midge larvae. Stocking fish predators and enhancing the fish environment can increase predation and reduce midge numbers.

Editor’s note: This article, as well as the one at right, were adapted from Techletter, a biweekly publication from Pinto & Associates, Mechanicsville, Md. To subscribe, visit www.techletter.com, or call 301/884-3020.
 

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Check These Mosquito Breeding Sites

Often when customers complain of mosquitoes, they are surprised to find they are breeding them right in their own yard. Many people don’t understand that stagnant water is home to mosquito larvae. Either you or your customer should check these typical mosquito breeding sites:

Cans and Buckets. Discard them, store them inside or turn them upside down.

Old Tires. Store in a basement or shed where they won’t collect rainwater.

Barrels and Garbage Cans. Drain them and store tightly covered or upside down.

Roof Gutters. Clean out leaves and debris that trap and hold water.

Bird Baths. Change and clean the water every few days.

Wading Pools. Change the water every few days, but make sure that the water you dump out drains away. Turn upside down when not in use.

Canoes and Boats. Cover with a tight-fitting tarp, or turn upside down.

Ornamental Ponds. Stock with small fish that will eat developing mosquitoes.

Puddles and Swampy Areas. Grade to drain off the water, or fill with dirt.

Flower Pots and Vases. Drain standing water from pot saucers and change water in outdoor vases every couple of days.

Leaky Faucets and Hoses. Repair leaking faucets and drain area beneath.

Tarps or Plastic Sheets. Make sure that coverings on boats, swimming pools, compost piles, etc., are pulled tight and sloped so that rainwater runs off.

Pet or Livestock Watering Pans. Empty frequently, clean and refill.

Wheelbarrows. Store under cover in a basement or shed or upside down.

Drainage Basins. Remove stagnant water from sump pits, dry wells or drainage basins.

Cesspools and Septic Tanks. Make sure systems are tightly covered, operating properly and not overflowing.

Storm Drains. Check to see that water flows freely and is not blocked by leaves and debris.

Tree Holes. Remove stumps or fill stumps or tree holes with sand or other filler.

Source: Techletter