Like their uninfected counterparts, Mega Bites are attracted to blood, and will hunt down their prey. When caught, they attach themselves to the victim to feast on their blood. Any source of blood aside from living beings will also attract them.
Upon feasting on blood, they will grow significantly from their original size, from one foot to two meters. The same mutation can be caused by injuries. Once they've grown large, they no longer crave blood. They will instead hunt down their prey for their queen to eat, rather than to suck blood.
Fully grown Mega Bites will devote their lives to protecting their queen. If they think she is threatened, they will curl up into balls and roll at the enemy in hopes of crushing them to death.
Mega Bites are poisonous and will use their poison when feeding on their victims blood. This may be to kill or paralyze their prey for eating later. Other arthropods, such as spiders, use enzymes to digest the bodies internal organs for easy consumption later. A Mega Bite may have been the creature dragging Amelia into the vents.