...

Female mosquitoes have to sting and suck blood to produce a big number of eggs, they release as "boats" on surface of rain barrels.
Material
Tray, tea spoon, sieve, pipette, 3 ampoules (5 mL), jam jar (20 mL) as stand, water.
Experiment
1. Use a tea spoon to collect an egg "boat" from the surface of a rain barrel. Flush it onto the water surface of an ampoule (Fig. 1).
2. Observe it during the following days.
3. Catch big larvae from the rain barrel with a sieve. Transfer them into the second ampoule full of water (Fig. 2).
4. Study the movements in this small aquarium, try to raise pupae.
5. As soon as pupae appear in the rain barrel, take a sample of them.
6. Cover ampoule 3 loosely with a reversed stopper.
7. Look for hatched male (no proboscis) or female mosquitoes (Fig. 4).
8. Repeat 6 and 7 one or two weeks later. Compare.
Observation
for 2: After few days a big number of tiny white worms (egg larvae) jerk between the surface and the bottom of the ampoule.
         At their back ends they have a snorkel, they fix at the water surface.
for 4: The larvae grow very rapidly. They look like and behave like the egg larvae.
for 6: Pupae have the snorkel in the middle of their bodies.
for 7 an 8: At the beginning only male mosquitoes appear (Fig. 4), later on more and more females are hatching.
Explanation
All stages of development in water have to get in direct contact with air for respiration. In order to find food the larvae have to dive to the ground.
The males suck juices from plants. They are ready for mating when the females are hatching. ..