The only effective way to kill maggots permanently is to use boiling water, or a disinfectant like bleach, vinegar, or insecticide. Boiling water should be poured directly onto these insects to ensure they are submerged and exposed to the boiling water for several minutes.  If using bleach, vinegar, or insecticide, the chemicals should be sprayed directly onto them until they are soaked. These chemicals will kill the maggots on contact.