One of the best known metabolites of DDT in insects is DDE. This is primarily due to work that demonstrated that the major cause of DDT-resistant houseflies is the ability to dechlorinate DDT to DDE. The enzyme responsible for this biochemical reaction is DDT-dehydrochlorinase, which has been isolated, purified, and many of its properties are being studied. The mexican bean beetle, which is normally very tolerant of DDT and related compounds, has a relatively high titer of DDT-dehydrochlorinase. DDE is relatively nontoxic compared to DDT and is of little value as a pesticide.