Which two mosquito instars are targeted by chemical control methods?

Chemical control methods primarily target the larval stage of mosquitoes, which is the immature form, along with the adult stage. The larvae are particularly vulnerable because they depend on water for their development; it is during this time that they are exposed to larvicides, which are pesticides specifically designed to eliminate immature stages of mosquitoes. Additionally, adult mosquitoes are often targeted because they are the reproductive stage that can spread diseases and infest areas.

Focusing on these two life stages allows for effective control of mosquito populations, reducing their ability to reproduce and spread disease. Larval control involves treating breeding sites, while adult control may occur through various means, such as space spraying or applying residual insecticides.

Other options, which may mention targeting eggs or pupae, do not align with the primary chemical control strategies used in mosquito management. Eggs are often not directly affected by chemical treatments until they hatch, while pupae are less frequently targeted as they are more resistant to many chemical controls and are a short-lived stage just before adulthood.