Mosquito and its life cycle

  • Mosquitoes are two-winged flying insects that suck blood from humans and other animals.
  • They are found all over the world but are mostly common in humid and temperate climate.
  • They are generally found in the dark places such as bushes, holes in the trunk of the trees, corners of the room, bookcase, near ponds and ditches.
  • Nowadays they are also found at the higher altitudes than the mild hilly regions due to climate change.
  • They are carriers of a number of diseases, mostly in the tropics, causing illness and death on a large scale.
  • They are nocturnal in feeding habit but in day time biting also occurs.
  • Some species prefer biting at certain hours, at dusk and dawn or in the middle of the night.
  • Female generally feeds on blood of humans and animals and male feeds on fruits and flower juices.
  • For that reason female mosquitoes are only responsible for causing diseases not the male.
  • Female mosquito has piercing and sucking type of mouth parts while male has only sucking type of the mouthparts.
  • They can fly a long distance in a single day, about 20-30 km in a night and about 2 to 3 hours continuously without rest.
  • Culex tarsalis and Anopheles freeborni are the two main types of mosquitoes which are common in Nepal.

A)External morphology

  • They have a small, soft, slender body, long jointed legs, needle shaped piercing and sucking mouth parts and body covered with minute scales.
  • It measures about 3-4mm in length and the body is grayish-black in colour.
  • The body is divided into three regions: head, thorax and abdomen.
  • The head of the mosquito is very small and almost spherical which is connected to the thorax by means of short and narrow segment or neck.
  • It bears a pair of kidney shaped compound eyes, a pair of antennae and the mouth parts called the palps and the proboscis.
  • The eyes are comparatively big in proportion to the head.
  • Each of the antennae is made up of 13 segments with whorls of hairs.
  • The second segment of each antenna possesses the hearing organs called Johnston’s organs.
  • Male has long hairs as compared to female on their antenna.
  • The thorax consists of three regions: very small prothorax, large mesothorax and small metathorax.
  • Each segments of thorax consists of a pair of long jointed legs and mesothorax consists of a pair of wings with halters or balancers.
  • The wings are larger in the female than in the male.
  • The vibration of wings results in buzzing sound.
  • The abdomen is slender and made up of 9 segments.
  • An anal opening and a genital opening is present in abdomen.
  • The 9th segment of male bears an anal style that helps in copulation.


  • Mosquitoes have four distinct phases in their life cycle: egg, larvae, pupae and an adult.
  • They show complete metamorphosis in their life-cycle as they have all phases.
  • The two sexes copulate during flight in the evening where the male gets attracted to the female by her high-pitched whine.
  • The female usually mates only once but produces eggs at intervals throughout their life.
  • In order to be able to do so, female requires blood meal.


Image result for life cycle of anopheles mosquitoImage result for life cycle of culex mosquito




  • A female mosquito lay about 30-300 eggs depending upon the species at a time.
  • The female anopheles lay about 30-100 eggs at a time which are laid separately and horizontally on the surface of water.
  • The eggs are spindle shaped having lateral air floats.
  • Similarly, a Culex lays about 200-300 eggs at a time which are glued together to form a small floating raft.
  • The eggs of Culex are cigar-shapede. their upper end is narrow and pointed while the other end is broad and rounded.


Image result for eggs of culex                                              Image result for eggs of anopheles



  • The eggs are hatched into larvae within 2-3 days under suitable condition.
  • These are transparent and emerge from the lower end of each egg.
  • They show caterpillar-like movement so they are also called wrigller.
  • The body of larva is divided into head, thorax and abdomen.
  • The head bears of a pair of compound eyes and mouthparts.
  • The front part of the mouth possesses feeding brushes which help to feed.
  • The thorax is broad, un-segmented and has no appendages.
  • On the lateral sides, three pairs of tufts of hairs are present.
  • The abdomen is made up of nine segments each of which bears bristles.
  • The dorsal side of eighth segment possesses a siphon which bears a pair of
  • Spiracles help in respiration.
  • Tracheal gills are present in ninth segment around the anus.
  • This stage lasts for about 2 weeks during which it moults three to four times enlarging its size with each moulting.
  • The larva of culex at rest hangs at an angle from the surface of water whereas the larva of an anopheles lies parallel to the surface of water.
  • The fully grown larva lives in water and develops into pupa.


Image result for larvae of culex                   Image result for larvae of anopheles mosquito

larvae of Culex                                                                   larvae of Anopheles



  • Commonly known as tumbler.
  • Body is comma shaped and can be divided into anterior swollen part called cephalothorax and the posterior elongated hook-like abdomen.
  • The pupa is enclosed in transparent membrane called puparium.
  • Pupa of mosquito is very active as compared to other insects.
  • It always swims with the help of its paddle.
  • Mouthparts are absent so it does not feed on anything.
  • It respires with the help of respiratory trumpets.
  • It lasts for about 2-7 days during which the adult organs are developed.


Image result for pupae of culex mosquito                    Image result for pupae of anopheles mosquito

pupa of Culex                                                                                            pupa of Anopheles



  • The pupal stage lasts for short duration.
  • The pupa develops the body organs inside it after the completion of the metamorphosis.
  • Thus, a perfect adult insect, an imago is formed.
  • The mosquito is completely young in this stage which emerges when the pupal skin splits.
  • The wings get dried by vibrating after which the mosquito flies in air within 5-10 minutes.
  • The male and female mates and the female gets ready to lay eggs again.
  • In this way the life cycle of mosquito continues.


Image result for adult culex                   Image result for adult anopheles

adult Culex                                                                                                      adult Anopheles


Mosquito and its life cycle

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