Is The Mosquito A Difficult Pest To Control?

Question 1: What should I know about mosquitoes before treating them?
Mosquitoes are two-winged, bloodsucking flies that are primary disease vectors. They feast on blood to obtain protein for egg production, often spreading disease to the host. Interestingly, they also feed on the plant nectar for energy.
 
Adult mosquito’s wings beat at 200-300 times per second creating a high-pitched whine that sends cold shivers down your spine. They are fast and -often heard before they’re seen. 

Generally, a mosquito needs water to complete its lifecycle. This can range from rot holes in trees to large lakes or salt marshes. Even subterranean water sources can support very large mosquito populations. Some mosquito eggs can dry out completely but still remain viable for considerable periods, waiting for the necessary moisture to complete the larval stage.

In my experience, people don’t associate the larval ‘wriggler’ with the mosquitoes that bite them. Under a microscope, they don’t resemble the adult form at all. As Professional Pest Managers it’s our duty to educate customers. Help them understand and treat all stages of the lifecycle, while ensuring they appreciate the risks mosquitoes pose to human health. 

Question 2: What should I look for during my inspection?
The simple answer is water sources.

- Around a domestic home or commercial business there are always areas of moisture pooling, creating the perfect larval habitat:
- Blocked drains, gutters, downpipes 
- Bird baths 
- Pot plants - even plants like bromeliads 
- Kid’s toys 
- Fish ponds and water tanks 
- Water troughs 
- Stored items such as tyres, buckets, pipes…. 

The list is long but in no way complete. There can also be internal sources such as unused spa’s, plants, unmaintained fish tanks, floor drains, etc... Tipping out the water removes the breeding site but consider how the water got there in the first place and will it return once you have gone? You cannot be there every day to tip it out.

Question 3: How far do adult mosquitoes fly from their breeding site?
It depends on the species but adult Aedes have been found 160km out to sea. It’s probably not the norm but prevailing winds influence just how far they reach.

A US study with 250,000 marked Culex Tarsalis found most were taken within a 2-mile radius; however, the great majority were taken downwind within a 10-mile radius. Like all small species of flies, dispersal and survival can depend on moisture and they die quickly in hot and dry conditions.

Housing on the edge of a breeding area may experience “swarms” of mosquitoes when prevailing winds come towards the house. This swarm can survive for long periods in moist, shady gardens and can even breed if localised water is available.

When nuisance biting species are involved, it makes the homeowner’s life quite miserable. Hounded every time they leave the house, we are often called upon to provide relief.

Question 4: What Treatment Options exist for the Professional Pest Manager?
Effective treatment depends on the situation at hand. Because larvae exist on water, you must be careful when using insecticides. Most of the available chemistry has very specific limitations when applied around waterways.

Different types of treatment available include:
• Government programs exist to treat sensitive waterways. They use a crystal from a special bacterium that is effective at killing larvae without affecting other marine organisms.

Highly specialized work, it requires considerable resources like helicopters to treat large breeding areas. This is not usually a PPM activity but it’s good to be aware of the programs in your area.

• Space Sprays are designed to kill adult mosquitoes on the wing and are very effective at quickly taking out large numbers of adult mosquitoes over very large areas.

Space sprays are small micron-sized insecticide clouds that leave no residual chemical in place once they have dispersed. To be effective, they must be applied during periods of high insect activity and very low wind conditions. Insecticide cloud drift away from the target area results in poor control and possibly detrimental effects on non-target insects.

• Residual barriers deposit active ingredients onto resting surfaces to kill mosquitoes coming to land. External and internal walls, furniture, fences, vegetation, etc., are typical treatment surfaces. They effectively place a barrier or killing zone between a major breeding source and a residential area. Ideally, reducing the number of mosquitoes in the vicinity of the dwelling which should translate into far less nuisance biting and very low disease transmission risk.

• Residual Impregnation uses a residual chemical to impregnate clothing, tents, mosquito nets, etc., killing mosquitoes landing on treated materials. Fabrics are soaked in a chemical emulsion and dried before use. Factory impregnation is also used when treating mosquito nets.

• Personal repellent is a very effective tool for preventing bites. Its role is limited in mosquito management but eliminate biting and you reduce the chances of disease transmission. Ensure that all staff involved in mosquito work are always protected by personal repellent.

• Insect screens play a major role in mosquito control. In good condition, most modern screens provide every effective control but smaller biting insects such as midges may still penetrate the fine mesh. A small hole in the screen renders it ineffective.

In the future, expect insecticide treated screens that are more effective and will compensate for the loss of efficiency when small perforations are present. Currently, you must apply residual chemicals to existing screens to create the extra protection required for smaller biting flies. This treatment can be quite simple if the screens are easily removed but when treating them in situ be very careful with insecticide treatment around glass surfaces.

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