Well, both tend to feed on already decaying things, so I'd say that the body is at least 20 to 50 days after death. Beetles normally take over around that time because maggots can no longer get through the dry tissue.
Saliva gland is held physical and chemical digestion
Soil
Soil is the upper layer of the ground comprising of a mixture of sand, silt, clay, loose rock fragments, and organic matter that can support the growth of rooted plants. The relative proportions of sand, silt and clay determine the texture and size of the pores of the soil, which affects its ability to allow air and water to penetrate/infiltrate.