Mosquitoes, Gnats, Horseflies
Mosquitoes & bloodsuckers
The mosquito is a dipteran insect of the Culicidae family with approximately 3,500 species worldwide. In Greece, there are at least 59 different species of mosquitoes, but they do not all occur at the same time.
The Culicidae family is divided into three subfamilies:
- Anophelinae, which includes the genus Anopheles, with species that transmit malaria to humans.
- Culicinae, which includes genera such as Aedes, Culex, Culiseta, Psorophora and Mansonia.
- Toxorhynchitinae, with species of non-blood-sucking mosquitoes, whose larvae are considered beneficial as they are predatory and feed on larvae of other mosquitoes of the Culicidae family.
Biology.
The male mosquito has more densely hairy antennae than the female. Mosquitoes feed mainly on nectar or pollen, but females also need blood to mature their eggs. After a blood meal, the female deposits her eggs, usually on the surface of the water.
The eggs hatch into larvae, which are aquatic and feed on organic debris or even other insects. They have special respiratory systems that allow them to breathe both in and out of water. They then pass into the pupa stage, from which the adult insect eventually emerges.
Mosquitoes are attracted to movement, body temperature, humidity and carbon dioxide and are most active in the early morning/evening hours. The female pierces the skin with special “pins” and sucks blood through her proboscis, leaving an itchy saliva. Mosquitoes prefer dark-colored skin.
The genera
The useless one – Anopheles sp.
It is the vector that transmits malaria, encephalitis and filariasis. Adults have a body length of about 5 mm and are recognized by their characteristic straight posture, with the proboscis, head and rest of the body in the same line. Their wings also bear small marks.
When a female Anopheles bites a person with malaria, along with the blood it sucks in the disease agent, the plasmodium. Inside the mosquito's body, this microbe develops and is then transferred to the salivary glands. Thus, with a new bite on a healthy person, the mosquito transmits the malaria agent through its saliva.
The Anopheles mosquito has a lifespan of approximately 18 days to 4-5 weeks.
The common mosquito Culex sp.
The Culex mosquito breeds in stagnant and polluted water, as well as in areas with high humidity. It has a characteristic broken proboscis that forms an angle with the rest of its body downwards. Its wings are uniformly coloured. The female lays her eggs in groups of 100 or more on the surface of the water, where they float.
The Culex mosquito has a lifespan of 10-15 days, although it can live longer in cold conditions. It is a vector of encephalitis, although it transmits it relatively difficultly. In tropical areas it can also transmit filariasis (parasitic elephantiasis).
The genus of aedes Aedes sp.
The Aedes mosquito transmits yellow fever as well as other serious diseases. It is distinguished from common mosquitoes by the silver color on its thorax.
Aedes larvae are short and stout, while its eggs have the ability to survive out of water for a considerable period of time.
Aedes reproduces after floods, in rainwater tanks or in salt marshes.
Its lifespan is usually short, 10-15 days, although under suitable cold climatic conditions it can live up to a few months.
The Tiger mosquito – Aedes albopictus
Aedes albopictus is perhaps the most discussed mosquito species internationally in the last two decades. It attacks humans mainly during the day, with increased activity at dusk. Females prefer to bite in the ankle and knee areas and, in addition to humans, they readily bite other mammals and birds.
In Europe, it first appeared in Albania in 1979, then in Italy in 1990 and France in 1999. In Greece, it was first found in 2003 in Corfu and Thesprotia, while in 2008 it was also detected in Astakos, Aitoloakarnania. Since then, it has spread widely, including in Attica.
Aedes albopictus is not a new species, nor is it the only one that transmits serious diseases such as dengue fever. However, it has been shown to carry many pathogens such as Chikungunya, Japanese Encephalitis, West Nile, yellow fever, as well as the nematodes that cause filariasis.
In a short time, it has gone from being an endemic species of Southeast Asia to one of the most dangerous mosquitoes in the world, thanks to its amazing ability to easily spread to new habitats and transmit diseases to these regions. Its mobility by flight is limited, so its main mode of dispersal is passive transport, e.g. through the trade in used tires.
West Nile Virus: The majority of people infected with West Nile virus remain asymptomatic. About 201% of those infected experience mild flu-like symptoms. Fewer than 11% of cases develop more serious CNS symptoms, such as encephalitis, meningitis, or acute flaccid paralysis. The most severe cases usually occur in the elderly and in patients with suppressed immune systems.
Treatment & Control: Unfortunately, fighting mosquitoes is not easy. It requires constant spraying with expensive and resistant drugs, without always having a 100% result. This is because:
The medicines sprayed in inhabited areas are called medicines of sanitary importance. These either dissolve if water falls on them or break down if the sun hits them. Given that mosquitoes survive and lay their eggs mainly in open spaces (yards, gardens, balconies, etc.), spraying with insecticides in a place where the sun or rain falls will not last long.
Insects do not recognize property. No matter how well we spray, if our neighbor does not make an effort to control them, the problem will be significantly reduced but will not be eliminated.
Therefore, dealing with mosquitoes should be preventive, continuous and collective.
Prevention
An important measure is to identify and eliminate hotspots where mosquito populations thrive, whether on a small or large scale. This includes reducing areas of standing water, from eliminating pots and pans to draining marshes or ponds.
In addition, it is necessary to deal with blockages in the sewer networks and repair water leaks. Other measures include reduced watering of gardens, pruning of dense vegetation, control of native flora and frequent mowing of lawns.
Finally, to prevent mosquitoes from entering buildings, it is recommended to install screens on doors/windows, use air curtains, etc.
Larvicides: In the spring, we begin sampling stagnant waters. The goal is to combat populations early, so that they do not develop in large, uncontrolled quantities. If larvae are detected in a concentration, it is recommended to apply a larvicidal growth regulator to the specific water body.
Acacias: Residual sprays are not effective. Instead, direct sprays with pyrethrins are recommended on all surfaces frequented by adult insects. However, their use should not be uncontrolled. The problem cannot be treated solely with adulticide sprays.
Mosquito Capture – Trapping: Even if we have taken all the necessary preventive measures and do not have mosquitoes in our area or if we have effectively treated them with larvicides and insecticides, there is always the possibility that mosquitoes will come from neighboring areas.
To address this issue, we can use special traps to catch mosquitoes that enter our space. This method is a complementary solution to the other measures.
In addition, small or large electrical devices are commercially available that emit carbon dioxide (CO2) and use special lighting to attract and trap mosquitoes, showing good results.
Mosquito Repellent: The last line of defense, when previous measures were not sufficient or we are outside our area of responsibility, is the use of mosquito repellents or devices.
Various types of repellents are commercially available, such as snakes, tablets for electrical appliances, devices with ultrasound or radiation, bracelets, special lamps and finally, spray preparations for spraying on bare areas of our skin.
Phlebotomists – Midges
They belong to the family Psychodidae and there are 700 species. The genera Phlebotomus, Lutzomyia and Sergentomyia suck blood from vertebrates and are of health importance as they are possible or proven carriers of leishmaniasis.
They are small insects, up to 5 mm long, slender with long legs and a hairy body. Their wings are lanceolate and their mouthparts are short. When resting, they place their wings at an angle above their abdomen, forming a V.
Females need bloodsucking to mature their eggs, while males do not bite. They bite mainly at dusk and at night, while during the day in shady and damp places. Their dispersal radius from the outbreaks can reach several hundred meters. They overwinter in the 4th generation larval stage. The larvae feed on various organic substances and their biological cycle lasts from 20 to 40 days. Before sucking blood, they secrete saliva onto the host's skin, which contains anticoagulant substances.
Mosquitoes are vectors of serious diseases such as leishmaniasis, three-day fever, and Bartonella bacilliformis (in South America).
Leishmaniasis, also known as Kala azar, is considered one of the most common infectious diseases of dogs in Greece. It is caused by the parasite Leishmania infantum, which is transmitted to dogs by female mosquitoes. It usually affects adult dogs over 6 months of age, regardless of gender or breed. In addition to dogs, the disease has also occurred in other animals such as wild carnivores, sheep, cats, rodents and humans.
Symptoms in dogs include fever, hair loss (especially around the eyes), weight loss, skin ulcers, abnormal nail growth, anemia, arthritis, and kidney failure that can lead to death. Available treatments only help control the symptoms and do not completely cure the disease.
The treatment of midges focuses on combating adult mosquitoes, through residual spraying of surfaces, placing screens on doors and windows, using mosquito nets, fans, room repellents and personal protection measures.
Tabanidae (horseflies), Horseflies
Horseflies or davanes belong to the Order Diptera and the family Tabanidae. They are cosmopolitan insects, with many genera and 4,000 species worldwide. The subfamily Chrysopsinae includes the genus Chrysops, while the subfamily Tabanidae includes the genera Haematopota and Tabanus.
Description: They are medium to large in size (6-30 mm), with species of the genus Tabanus being the largest and most robust, with a wingspan of up to 6.5 cm. Their coloration varies, often with stripes. Their antennae are short and strong with three segments, useful for distinguishing genera.
Biology: Females feed on sugary substances and seek blood by sucking humans, mammals, amphibians, reptiles and birds for their egg laying (100-1,000 eggs) on the underside of leaves etc. objects. The eggs are covered with a hydrophobic substance and the larvae fall into the mud, identified by the protruding rings.
Relationship with humans: Their bite is very painful and annoying for humans and animals. They are mechanical vectors of animal diseases such as anthrax, anaplasmosis, tularemia, etc., while in humans they transmit the eye nematode Loa loa (Chrysops).
Treatment: Their treatment is very difficult. Drainage of marshy areas, colored attraction traps and geraniol repellents in collars for humans and animals are recommended. Controlling the larvae is difficult as many species live below the soil surface.
