Other villagers object to DDT spraying because it does not kill cockroaches[1] or bedbugs;[2] rather, it excites such pests making them more active,[3][4][5][6] so that often the use of another insecticide is additionally required.[15] Pyrethroids such as deltamethrin and lambdacyhalothrin, on the other hand, are more acceptable to residents because they kill these nuisance insects as well as mosquitoes.[13] DDT has also been known to kill beneficial insects, such as wasps that kill caterpillars that, unchecked, destroy thatched roofs.[14]