One of the greatest determinations in the potential longevity of a zombie plague would be the life span of the zombie themselves. That is, the length of the plague will depend on how long individual zombies are capable of moving and spreading their infection to new hosts.
One of the most significant factors in this equation will be how long it takes the zombified corpse to decompose.
Decomposition, or the break down of plant and animal bodies into their base materials, is affected by several factors including:
l. presence of insects
2. microbial activity
3. moisture levels
Insects, specifically carrion feeders, play a vital role in decomposition as they consume much of the ﬂesh and soft tissue of a corpse. In fact, it has been documented in some areas that dense insect populations are capable of reducing a body to bones in mere hours. Assuming that a zombified corpse is essentially the same as a standard corpse, insects could feed on the zombie’s ﬂesh and organs, quickening the time in which they would decompose.
However, a few factors might play a part in mitigating this process.
l . Movement: The zombies own movement might serve to keep some insects at bay. One need only observe the common houseﬂy to see that they will retreat from the slightest movement.
2. Inedibility: Whatever causes the reanimation of the zombie corpse might render it inedible to insects. Without the assistance from insects, decomposition times could be extended signiﬁcantly.
3. Pseudo-life: It should also be noted that maggots (larval ﬂies) do not eat living ﬂesh. Historically, maggots were used medicinally by placing them into wounds. The maggots would eat the dead ﬂesh, leaving the living tissue intact.
If zombies have some residual life functions, (i.e. circulation, respiration) it might be sufficient to prevent the maggots from consuming the ﬂesh.
(This article appears in its entirety in Zombie Apocalypse Monthly Issue 1. It can be downloaded for free here: http://www.magcloud.com/browse/issue/391061.)