Chrysomya’s primary importance to the field of medico-criminal forensic entomology is due to the genus’ reliable life cycle, allowing investigators to accurately develop a postmortem interval.

Chrysomya adults are typically metallic colored with thick setae on the meron and plumose arista.

Identifying traits of the genus Chrysomya include: Keep in mind, however, that not all species will conform completely to these guidelines.

The larvae of one species, Chrysomya rufifacies, have very distinct thornlike processes covering its entire body, giving it the common name “hairy maggot blow fly”.

[4] The hairy appearance of C. rufifacies makes it easy to distinguish 2nd and 3rd instars from close relative, Chrysomya megacephela.

This life cycle is extremely short, and therefore valuable in determining an accurate post mortem interval in forensic entomology.

Depending on temperature, the entire life cycle, involving development from egg to adult, takes only between 190 and 598 hours.

If females participate in group oviposition, the results are much larger masses containing thousands of eggs that may completely cover a decomposing carcass.

During this time, the larval skin, which was initially milky white, actually shrinks and hardens to form a dark brown puparium.

As temperatures increase due to global warming, colonies of C. rufifacies are predicted to spread well into southern Ontario and Quebec.

C. megacephala is one species that prefers higher temperatures and undergoes the bulk of activity during peak heat periods of the afternoon.

Third instar C. rufifacies larvae are capable of potentially expelling other maggots from a feeding site with use of their large fleshy tubercles.

The easiest way to distinguish C. rufifacies from C. megacephala is to examine the anterior thoracic spiracle, on the adult fly’s body.

[1] C. megacephala are typically a shorter, more stout bodied fly with its tell tale signs being a larger head and prominent red eyes.

However, C. rufifacies can have the opposite effect since its second and third instar larvae are known to be predacious, feeding on other maggots that might have colonized the body first.