Scarabs are small, carnivorous insects that eat the flesh of whatever creature they could catch, particularly humans. The scarabs appeared in the City of the Dead, Hamunaptra, where they were used in the ritual of the Hom-Dai, and were worshipped by the ancient Egyptians as the bringers of the sun. read more
The scarab beetles in "The Mummy" are different: they voraciously feast on meat, especially the meat of trespassers and anyone unlucky enough to encounter them. They gather in groups, while normal scarab beetles are more solitary. They also appear different, having parts of other insects on them. read more
Scarabs are just a form of beetle and they are harmless to humans. The scarabs in the "Mummy" series do not exist in reality, as real scarabs do not have any inclination to burrow into living flesh. You've simply been alarmed by a reasonably believable CGI trick. read more