Amongst the things we need is DDT. Birds do not bite people. Mosquitos bite birds AND people.
Well yes, we need DDT back, but in this case mosquitos are not a vector in these flu epidemics. The flu is transmitted through physical contact with poultry and other bird livestock and then from person to person. Swine can often serve as the third leg of this dangerous vector cycle.
The DDT would be useful in fighting things like West Nile Virus which is not a flu.