Mosquitoes are holometabolous insects. The complete life cycle of mosquitoes takes about 13–15 days to complete.
Anopheles lays eggs horizontally and singly on the water surface. Eggs are
boat-shaped, having 2 lateral air floats, which help in floatation. In Culex, the
eggs are laid in clusters on the water surface, forming rafts. The egg in Culex
is cigar-shaped, without lateral air floats.
The eggs hatch after 2 to 3 days, and a small transparent larvae measuring
about 1 mm emerges. The larvae of mosquitoes are popularly known as wriggles.
Its body is divided into head, thorax, and abdomen. The head bears a pair of
compound eyes, a pair of simple eyes, a pair of 2 jointed antennae, and the
chewing mouthparts. The thorax is slightly broader than the head and bears 3
pairs of lateral tufts of hair. The abdomen is segmented into 9 parts. The larva
contains long respiratory siphons. It undergoes 4 moults and 5 instars.
Pupa, or tumblers, are motile. The head and thorax form the cephalothorax,
which has a pair of trumpet-shaped breathing tubes. The body is commashaped.
The abdomen consists of 9 segments, with palmate hair and caudal
fins on the eighth segment for swimming. The pupa remains at the surface for
about a day before the adult emerges. After 48 hours of the pupal stage, the
pupal skin splits and the mosquito emerges as an adult.
The adult uses air pressure to break open the pupal case, and crawls to a
protected area and rests while its external skeletal hardens, spreading its wings
to dry. Males are smaller; mouthparts are not adapted for sucking. The abdomen
is smaller. The female mosquitoes are bigger in size than the males. Their
mouthparts are adapted for blood sucking, which is essential for the development
of ovaries/eggs. The males feed on nectar from flowers. The thorax bears 3 pairs
of legs, 1 on each segment, and a pair of wings on the mesothorax. Wings on
the metathorax are modified to halters. Adult females live for a month and adult
males for a week.