In insects and houseflies DDT is converted to

In insects and houseflies, DDT is converted to DDE.
Dichlorodiphenyltrichloroethane (DDT) is an insecticide used in agriculture.
When applied to soil DDT is digested by bacteria and slowly converted into DDE, which is even more persistent in the environment than and at least as toxic as DDT.
In insects, the best known metabolite of DDT is DDE, the ability to dehydrochlorinate DDT to DDE is the major cause of the resistance of DDT-resistant houseflies.