Forensic entomologists, of course. These are the strong-
stomached folks who study the arthropod fauna that colonizes
dead flesh. Their knowledge of insect taxonomy, ecology, and
development can be used to provide estimates of the time and
conditions of death. Or zombification, in the present case.
Hypothetically, suppose a zombie shuffles along to my house at
horrifying rate of 1 km/hr. On arrival, I note that the zombie
is infested with final instar larvae of the blow fly Phormia
regina. Under our current warm summer weather conditions, it
takes at least 5 days for the maggots to reach that
developmental stage since momma fly visited the zombie. So we
can presume that the zombie has been decomposing for at least
that long. Let’s see. 5 days is 120 hours. Shuffling at 1km/hour
would put the origin of that zombie no further than 120
kilometers away. If we collect maggots and crunch the numbers
from enough zombies, we should be able to triangulate in on the
location of the zombie epicenter. The zombie control f