Dealing with Mosquitoes

 Dealing with Mosquitoes 

Asian Tiger Mosquito Andes albopictus 
Source: Centers of Disease Control and Prevention (CDC)

Mosquitoes are a part of life in Southeastern North Carolina and they can be both a nuisance to people and a potential danger to birds. At the same time, most of our native mosquitoes are beneficial to the landscape as they provide food for predatory insects, spiders, and even birds, while some species pollenate flowers. In this week's article, I will discuss the ways that we can deal with mosquitoes without resorting to harmful pesticides. 

Mosquitoes

Mosquitoes (Family Culicidae) are small to mid-sized insects that belong to the insect order Diptera and are in the same group as houseflies, hoverflies, and midges. All of these insects have a single pair of wings and differ from flying insects like bees or wasps (which have two pairs of wings). There are hundreds of species of mosquitoes in North America although only a small handful bite people or pets. In the Cape Fear Region, the main nuisance mosquito is the Tiger or Day Mosquito Ades albopictus which is common in Wilmington from April to as late as December depending on how cold it gets. A few other nasty species include our native Culex mosquitoes (like the House Mosquito), Floodwater Mosquitoes (Andes vexans) and the giant Psorophora (commonly called Gallinippers) which mainly occur near wetlands or after major rain events like tropical cyclones. Outside of these examples, many species are relatively harmless and some do not bite people at all. Mosquitoes are not to be confused with the large but harmless craneflies, predatory robberflies, or swarms of midges as none of these bite people. 

Lifecycle 

Mosquitoes are fascinating species from an entomology standpoint and like butterflies they undergo metamorphosis. All mosquitoes require water to breed and complete their larval and pupal stages in bodies of stagnant water. Most of our native species breed only in puddles, vernal (temporary) ponds, tree holes, or in flooded meadows and rarely survive in water features with fish, or aquatic insects (dragonfly larvae, water scorpions etc). Because of this, most of the woodland and meadowland mosquito species only bother us when we are hiking, kayaking or happen to live next to such an environment. Species that breed in floodwaters or puddles may become abundant days or weeks after hurricanes or major rain events but are temporary issues. The only mosquito that is a major problem in our gardens is the Asian Tiger Mosquito which is a nonnative species introduced in imported tires and other objects that carry water. Most species complete their development in 1-2 weeks while the Tiger Mosquito can go from egg to adult in just 7 days.

Breeding Habitat: Most mosquitos choose marshes, stagnant ponds, or other wetlands for habitat and stick to natural areas. The Tiger Mosquito can breed in any body of water including rainwater that collects in flowerpots, clogged gutters, or rubbish left on roadsides. A bottle cap may provide enough water this species to breed, and forgotten flowerpots or old tires can become mosquito factories. In general, mosquitoes avoid moving water and environments with fish.

Range: Most mosquitoes travel only a few hundred meters from their breeding source and mostly bite victims within that radius. Saltmarsh Mosquitoes and Floodwater Mosquitoes can travel very long distances but are little more than nuisances and are most common after hurricanes. In most cases if you are being bitten by mosquitoes the source is not far away. 

Breeding: The breeding cycle of mosquitoes is similar to other insects. Mosquitoes protein to develop eggs which is why some species bite other animals. After mating, the eggs are laid on bodies of water or nearby vegetation and will hatch shortly after. The eggs may of some species  remain inactive for long periods of time until they come in contact with water. Larvae consume detritus and resemble small worms that have breathing siphons on their tails. After pupating, they emerge as adults and restart the cycle. 

Ecological Role: While mosquitoes are often viewed for their annoyance or health risks, they have a role in our ecosystems. Aside from being a food source, the insects pollenate certain plants just like other flies, while their larvae consume detritus in ponds. In turn, mosquitoes can also cause harm to birds and wildlife. Overabundance of biting midges, mosquitoes, and blackflies can kill or weaken bird nestlings, reptiles or amphibians, and increase stress in large animals like deer. They can also carry diseases and parasites that can impact local ecology. Over abundance of mosquitoes in your garden can be bad news for birds as many avian borne diseases can be transmitted through mosquitoes. 

Controlling Mosquitoes

Properly working fountains rarely harbor mosquitos 

Mosquitoes can quickly become an issue in a garden or public area if they are left unchecked. While their bites are annoying or painful, some species can be vectors of disease. The insects can also weaken livestock, and lead to other consequences as well. Cities, counties, farmers, and citizens take many measures to control mosquitoes although most solutions rarely solve the problems, and are at best a temporally solution. Certain actions can lead to unintended consequences such as the loss of other insect species such as native bees, dragonflies and domestic honeybees in area hives. On a community level, county or state agencies may spray communities for mosquitoes to control disease vectors or treat ditches, floodplains, and other wet areas with larvacides to inhibit breeding. New Hanover County (NHC) for example only sprays when a disease communicable to humans or livestocks is detected and a population threshold has been met (based on scent traps, wetland survey and other sampling means). While homeowners can buy mosquito foggers, persistent insecticides or pay for a commercial mosquito service, pesticide applications should only be a last resort. Such actions can cause risks to native insects, reptiles, birds, or people sensitive to certain chemicals if done incorrectly or too often. Below are some measures to reduce or even get ride of mosquitoes in you garden without chemicals. All of these measures are simple tasks that can make a big difference for your family and your neighbors.  

Tip and Toss: The best way to control mosquitoes in your garden is to dump standing water and remove or cover anything that can hold water. Flowerpots, clay saucers, plastic tubs, and old tires are just some of the items that can harbor Tiger or Floodwater Mosquitoes. An object as small as a bottle cap can be enough for mosquitoes. Trash such as snack wrappers, cans, beer cans, or abandoned appliances may also host mosquitoes and should be cleaned up. According to NHC, most mosquitoes have a limited range and eliminating sources will reduce encounters with these insects. 

Clean Birdbaths: Birdbaths and other water features should be dumped out and refreshed daily and cleaned once a week. 

Moving Water: Larger water features such as fountains, garden ponds, and container marshes should be aerated with pumps or another device that keeps the water moving. Alternately you can stock garden ponds with fish to keep mosquitoes at bay. 

Organic/Home Remedies: Add organic or biological larvacides into containers of water you intend to keep or cannot easily tip or dump. These products are available in most hardware stores, and your county or town may even offer them for free at the government center. Mosquito control sticks often look like doughnuts and last for weeks or months at a time. You could also use dish soap, Castile soap, or another nontoxic (preferably organic) substance that makes it harder for mosquitoes to lay  eggs or prevents the larvae from breathing (if the container is not also being used by frogs or other animals). 

Cover Rain Barrels: Cover all rain barrels with screen or mesh small enough to keep mosquitoes from getting in. A Tiger Mosquito is 0.3cm (1/8th of an inch) and can get through some types of mesh. Keep the barrel from overflowing as well.

Natural Predators: Another solution for mosquitoes is to provide habitat for natural predators. Dragonflies, damselflies, lacewings, robberflies, certain wasps, and web-spinning spiders readily eat mosquitoes. Certain birds and reptiles may also eat mosquitoes in small numbers. In the water, dragonfly larvae, minnows, frog tadpoles, water scorpions, and  aquatic beetles eat mosquito larvae. Destroying wetlands to combat mosquitoes will only reduce the natural predators, and will not control nonnative mosquitoes as they can breed anywhere

Avoiding Mosquitoes   

It is best to hike near wetland forests during the midmorning 

The best way to minimize the risk of being bitten by mosquitoes or other biting flies is to avoid them in the first place. Most of our native species are active during a small window between dawn or dusk, or on overcast days. Avoid hiking in forests or marshes or wear protective clothing (long trousers, shirt, face netting if you have it) during peak times. The Tiger Mosquito, is mostly active during the daytime but stick to forests, shady areas, and areas with dense vegetation. Still these insects will be less active during the heat of the day or in open areas away from woods or brush. 

• Hike, walk, or exercise during the day as mosquitoes are most active at dawn and dusk

• Mosquitoes are more numerous in damp forests, wetlands, and other shaded habitats.

• Wearing long trousers, long sleeve shirts, and closed shoes will protect you from most mosquitoes (including Tiger Mosquitos), you could also use a face net. 

• Mosquitoes are less common from late October to early April in the Carolinas, and seem to peak around July, August, or September. 

• Mow grass and reduce dense undergrowth near the home to keep mosquitoes further away from doorways or outdoor areas. Invasive plant infestations (privet, wisteria, kudzu) provide lots of cover for mosquitoes but not native predator.

• Use a handheld bug zapper to kill biting insects around you without chemicals, be advised that wands can generate a shock if touched so do not touch the grid when the light is on.

• Use approved repellents, or home remedies such as Clove Oil or herbal solutions to repel mosquitoes or deal with bites. Please read the instructions, and seek appropriate medical advice before using any repellent or home remedy as some things can cause allergic reactions.