Dichlorodiphenyldichloroethylene is the full name of DDE which is a breakdown product of the pesticide DDT. The full name of this compound is 1,1-bis-(4-chlorophenyl)-2,2-dichloroethene, and this compound is formed by the loss of hydrogen chloride (dehydrohalogenation) of DDT 1,1-bis-(4-chlorophenyl)-2,2,2-trichloroethane.
DDE is a fat soluble substance which tends to build up in the fat of animals, while it is not an insectidide it is commonly found as a breakdown product of DDT.