Flies are very choosy as to what they will lay their eggs on, with some species preferring fresh meat and others that which has been left for a while. Temperature will influence incubation and maggot development. Maggots bought from fishing tackle shops will have reached the end of that stage of development, stopped feeding and have left their food source. If they are not at that stage they will be very near it. Further development - into pupa - is delayed by refrigeration. Maggot bombing might work - and please tell me if it does - but the result might be just a lot of sleepy maggots doing nothing on the site. If the carcass is near enough the surface and the temperature is right the flies will find it.
I have written this as a fisherman with some experience of maggots and of breeding them in small quantities in search of gaining an "edge" in competitions.
I have written this as a fisherman with some experience of maggots and of breeding them in small quantities in search of gaining an "edge" in competitions.