"Eruption" of beetle larvae(?) out of the ground.

Observation - "Eruption" of beetle larvae(?) out of the ground. - UK and Ireland. Description: I noticed a small mound of friable earth in the middle of a footpath. On closer examination it was f

I noticed a small mound of friable earth in the middle of a footpath. On closer examination it was full of what resembled beetle larvae, about 15mm long. Their colour was dark grey, very similar to crane fly larvae ("leatherjackets"). I wondered whether they were emerging from a carcase of a dead animal or bird that they had consumed.