All water bodies are natural habitats for
mosquitoes and black flies. Controlling these pests involves limiting conditions in the habitat that they find most accommodating, such as stagnant water and substrate to breed. ENVIROKONSULT™ makes use of a range of pesticides, larvicides and the application of environmentally friendly biological control products to manage biting insects. ENVIROKONSULT™ will determine the underlying causes of your pest infestation and develop a management plan to keep these pests under control.
Biting flies attack humans and animals to obtain a blood meal and can be very annoying. Some biting flies are also capable of transmitting disease. Biting flies of importance are sand flies, black flies, stable flies, mosquitoes, horse flies and deer flies. Around the aquatic environment the two most important pests are black fly and mosquito.
are small, dark, stout-bodied flies with a humpbacked appearance belonging to the order Diptera (Simuliidae). It hovers about the eyes, ears, and nostrils of man and animals, often alighting and puncturing the skin with an irritating bite. The adult females suck blood mainly during daylight hours and are not host specific. The black fly life cycle begins with eggs being deposited on logs, rocks, or solid surfaces in swiftly flowing streams and flowing irrigation canals. Larvae attach themselves to rocks or vegetation with a posterior sucker. The length of the larval period is variable depending on the species and the larval environment. The adults which emerge after pupation are strong fliers and can fly up to 5 km from their breeding sites.
Black flies suck pooled blood, injecting an anticoagulant that triggers mild to severe allergic reactions in most humans. The swelling and itch that follows lasts up to two weeks or more. Hordes of black flies pose a serious threat. Hosts sometimes die from acute toxaemia or anaphylactic shock. Black fly can cause various diseases in animals, as they are transmitters of pathogens (nematodes, protozoans and viruses).
Owing to their blood feeding habits and huge numbers, black flies are considered to be major pests in the livestock and labour-intensive farming systems in Southern Africa. The construction of dams, canals, irrigation schemes or hydro-electrical plants along rivers in South Africa increases the areas suitable for the breeding of black flies and has escalated the problem along the rivers to pest status. The Orange, Vaal, Great Fish River, Sundays River, Olifants River, Berg River, Eerste and Gamtoos Rivers and their surroundings in South Africa are known for problems with black flies.
Mosquitoes are a diverse group of insects also belonging to the fly order, Diptera (Culicidae). There are over 3,500 species of mosquitoes which can be found on every continent (except Antarctica). In Southern Africa there are 113 known species of mosquitoes, which can be found in a variety of habitats. Mosquitoes are not only the transmitting agents of malaria, yellow fever and dengue fever to man; they also transmit illnesses to animals.
Like most biting flies, both sexes feed on plant nectar but only the female drinks blood. She can detect prey up to 30-40 meters away and is attracted by carbon dioxide and lactic acid emissions, body temperature, dark colours, motion and floral scents. A mosquito requires blood protein to produce eggs, which she lays in marshes, ditches, puddles, slow moving rivers, lakes and ponds, ornamental pools, stock tanks and horse troughs, buckets, barrels and other water holding items. She can lie over 250 eggs per brood and prefers grass and weed-sheltered stagnant water.
Once the eggs hatch, mosquitoes develop through four larval stages as they feed and grow larger. They then progress to a non-feeding pupal stage and finally emerge as adults. The larvae and pupae breathe oxygen at the water’s surface by means of specialized, snorkel-like air tubes. These air tubes are called “siphons” in the larvae and “trumpets” in the pupae. One species of mosquito obtains its oxygen by piercing the fleshy underwater roots and stems of aquatic plants, such as cattails, and actually breathing through the plant. Mosquito larvae actively feed by filtering bacteria and organic matter in the water. The development from egg to adult depends on the water temperature and can take as little as seven to ten days in warmer weather.
Managing Mosquitoes Using Insecticides
Insecticides used for mosquito management are grouped into two categories. Larvicides/pupacides are used to control immature (larval or pupal) mosquitoes in aquatic habitats. Adulticides are used to control adult mosquitoes. The insecticides used are registered at The Registrar of Agricultural Remedies (Department of Agriculture) and do not pose any health hazards to humans or the environment when used in accordance with the label.
The control of black flies is typically aimed at the larval stages, and usually involves aerial applications of insecticides or physically altering the habitat of pest species. Black fly problems in irrigation canals and other water conveyance systems can be addressed with a chemical treatment of the target waters.
When it comes to insects, few are as annoying to man as the mosquito. From allergic reactions and infections due to a bite, to diseases such as malaria and encephalitis, mosquitoes spread misery everywhere they go. The female mosquito needs blood to produce eggs and a wet, protected habitat to lay eggs. Animals and algae provide everything they want, and for better or worse, lakes have an abundance of both. The natural way to limit mosquitoes is to make sure that the lake has natural predators, including several species of fish, birds and dragonflies. A healthy balanced aquatic ecosystem will go a long way towards keeping these mosquito feeders around. Chemicals may need to be used to control immediate mosquito infestations, but for long term control a healthy balanced lake is the best remedy. ENVIROKONSULT™ can help with a plan that includes larvicides, biological controls and aeration.
Contact us to get started on a plan to limit mosquitoes and/or black fly populations around your lake.