W20 Water butt
as habitat - Breeding Mosquitos Mosquitoes
(only females) make trouble to humans by sucking blood (Photo
1). In many areas
they are carriers of diseases like malaria and yellow fever. In the summer
season you can find growing stage of mosquitoes in water butts: Egg parcels
first, later on larvae ("worms") growing up to 1 cm length and still later
on pupae.
Material Tray,
water glass, insulin syringe 1 ml, 2 broad ampoules (5 ml) with stoppers,
2 high ampoule2 (5 ml) with stoppers, tea spoon, water butt.
Experiment 1. Use a teaspoon to transfer
an egg parcel from the surface of a
water butt to the surface of a broad ampoule full of rain water (Photo
2).
2. Collect grown up larvae
and pupae from the water butt with a tea glass.
3.
Use a syringe to catch larvae and pupae from the glass. Transfer them into separate
ampoules.
4. Cover the ampoules with
the reversed stoppers
5. Wait until significant
changes of the animals take place.
Observations
and explanations Left: A mosquito
put an egg parcel on the surface of
a barrel of rain water. Now it is floating on a 5 ml injection bottle.
After some days hundreds of tiny white worms are moving between the surface
(for breathing) and the bottom (searching for food).
Photo 2: In water
butts these larvae rapidly grow and
reach their final size. They can be seen in a 5 ml bottle attached to the
water surface using a snorkel for breathing air from outside.
Photo 3: A few day
later a rapid change of the body shape took place: Pupae
have their snorkels an the thicker front part of their bodies.
Right: Finally the
first males are hatching. They have
soft mouth parts. So they are unable to sting like the females which are
hatching later.
back.......go
on..................first
publication: 25.10.2001...........................................last
modification: 21.12.2008
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Experiment
3.
Use a syringe to catch larvae and pupae from the glass. Transfer them into separate
ampoules.