Mosquitoes will develop a resistance to DDT at the same time humans develop resistance to Malaria. That is, it will take a long time. In the meantime you can save a lot of lives.
This is categorically untrue, for a variety of reasons, not the least of which revolves around the reproductive cycle of a mosquito (2-3 weeks) versus that of a human being (~20 years).
Secondly, there are tons of observed instances of DDT resistance in mosquitoes. Sri Lanka, for one, is teeming with DDT resistant skeeters.
Vietnam stopped using DDT in 1991, yet their malaria rates plummeted. Why? Mosquito nets, distribution of anti-malarial drugs, and education (gasp!). They managed to reduce the death rate from malaria by 97% in six years, and the infection rate went down by 59%.
SW