Eggs

l            Adult mosquitoes lay eggs on water surface or its adjacent sites

l            Development of eggs take 2 to 3 days

Larva

l            Aquatic animal without legs

l            With four stages of development (1^st, 2^nd, 3^rd and 4^th instar)

l            Comes up to water surface to take atmospheric air with its spiracles at 8^th segment

Pupa

l            Non-feeding aquatic stage

l            Breathing through the trumpets at water surface

l            Lasts for 2 to 3 days

Adults

l            Body can be divided into head, thorax and abdomen

l            With a pair of jointed legs on each segment of the thorax and a pair of wings

l            Abdomen with 10 segments

Anopheles

l            Mosquitoes of this genus are capable of transmitting malaria in different parts of the world.  In Hong Kong, there are 11 species of Anopheles recorded.  Two of them were confirmed local vectors

of malaria. 

l            Anopheles minimus : breeds along slow running, clear water streams with diffused sunlight and marginal vegetation. Greater larval density is usually recorded in March to April and September to October.

l            Anopheles jeyporiensis : breeds in paddy fields, abandoned fields and water running through grasses.  Adults are most active around midnight.

Culex

l            29 species has been recorded locally.  Diseases such as Japanese Encephalitis, West Nile Fever and Filariasis are transmitted by this group of mosquitoes. 

l            Culex tritaeniorhynchus : breeds in pools, fishponds, waterlogged grass fields and ditches.  Adults are active at night with peak of activities one hour after dark.  It is a vector of Japanese Encephalitis and filariasis.

l            Culex pipiens quinquefasciatus : breeds in almost all types of water collections from highly polluted stagnant water, sewage, wet cultivations to small containers.  It is the most common and numerous mosquito both in the urban and rural areas.  It is a vicious night biter and is a strong flier.  It is a main vector of filariasis in South East Asia.

Aedes

l            The most commonly found Aedes mosquito is Aedes albopictus which is a known vector of dengue fever.  There are also other species of Aedes that are capable of transmitting other kinds of disease.

l            Aedes albopictus : breeds in small containers such as cans, discarded tyres, tree holes, rock pools, and bamboo stumps.  It is a daytime biter with rather short flight range of around 100m.  Adults can easily be distinguished by the white stripe on the dorsal side of thorax and bands on legs.  It is a local vector of dengue fever.

l            Aedes togoi : breeds in rock pools where sea water mixed with rain water.  It is an extremely strong flier and vicious night biter.  It has been incriminated as the secondary vector of Japanese Encephalitis.

u        remove containers that can hold water

u        properly cover containers that hold water

u        fill up bamboo stumps or tree holes with sand

u        avoid the use of saucer beneath potted plants

u        pave uneven ground surface

u        clear the surface channels regularly to prevent choking

u        keep mosquito fishes in pools or ponds

u        properly screen and cover septic tank

u        avoid accumulation of water in abandoned fields

u        prevent accumulation of stagnant water in water streams

n          Chemical methods :

u        By insecticides, e.g. temephos

u        By larvicidal oil

n          Biological methods :

u        By mosquito fishes

u        By biological insecticides e.g. B.t.i.

u        By Insect Growth Regular hormones

¡P     to use mosquito screen to prevent the invasion of mosquitoes

¡P     to use insect repellents to provide temporary protection from mosquito bite

¡P     to use mosquito coils or aerosol to kill the mosquitoes directly

¡P     to use fogging machine to knockdown mosquitoes in large-scale control operation or disease control