Anopheles mosquito larvae have a well-developed head with mouth brushes used for feeding, a large thorax, and a segmented abdomen. They have no legs. In contrast to other mosquitoes, Anopheles larvae lack a respiratory siphon, and for this reason position themselves so that their body is parallel to the surface of the water.
Larvae breathe through spiracles located on the eighth abdominal segment and, therefore, must come to the surface frequently. The larvae spend most of their time feeding on algae, bacteria, and other microorganisms in the surface microlayer. They dive below the surface only when disturbed. Larvae swim either by jerky movements of the entire body or through propulsion with the mouth brushes.
Anopheles larvae live in a wide range of habitats, but most species prefer clean, unpolluted water. Larvae have been found in:
- Freshwater and saltwater marshes
- Rice fields
- Grassy ditches
- The edges of streams and rivers
- Mangrove swamps
- Small, temporary rain pools.
Many Anopheles species prefer habitats with vegetation. Others prefer habitats that have none. Some breed in open, sunlit pools, while others are found only in shaded breeding sites in forests. A few species breed in tree holes or the leaf axils of some plants.
The Anopheles species pupae are comma-shaped when viewed from the side. In this stage of the life cycle, the head and thorax are merged into a cephalothorax, with the abdomen curving around underneath. As with the larvae, pupae must come to the surface frequently to breathe, which they do through a pair of respiratory trumpets on the cephalothorax. After a few days as a pupa, the dorsal surface of the cephalothorax splits, and the adult mosquito emerges.