Animated coloured scanning electron micrograph (SEM) of the tip of the cap of a mosquito (Culex spp.) egg case. Culex species lay their eggs in the form of egg rafts that float in still or stagnant water. The mosquito lays the eggs one at a time sticking them together in the shape of a raft. An egg raft can contain from 100 to 400 eggs. Larvae will hatch from an opening at the tip of each egg case. The eggs go through larval and pupal stages feeding on microorganisms (plankton) before developing into adult mosquitoes.