Blow Flies and Beetles: The Curious Life of Insects on a Human Cadaver

The sight of a human corpse exposed to waves of insect succession isn’t for the feint-of-heart. Their activity is relentless, never ceasing — until the last bits of soft tissue have been duly devoured and the body is left to dry decay. It’s a complicated production that interweaves several different species and life-cycles, with some creepy crawlies living out their entire lives on this strange, dark stage.

Entomologists spend careers closely studying the cast of characters involved in human decomposition; in reality, they are the accelerants in this process — biological catalysts, that if removed, would result in the body’s considerably slower breakdown. Whilst the specific species involved are highly dependent on the environment the cadaver first encounters (or is eventually left in), there are some commonalities among the key creatures involved.

So just who are these hungry, winged friends? It’s worth taking a closer look at their curious existence; when blow flies and beetles collide with our world, after death. If you’d like more on how to collect these specimens, we’ve got the entomological handling guide for you right here.


1. Calliphoridae and other stories

They’re probably the insect most closely associated with decomposition of any kind: blow-flies (otherwise known as carrion flies, bluebottles or greenbottles). Their scientific name is considerably more colourful in its pronunciation: calliphoridae. There are over one-thousand known species within this order; and they’re often the first insects to come in contact with decaying flesh.

A little known fact: they’re the pioneers in decomposition because they have a somewhat disturbing ability to smell dead animal matter from up to 2 kilometers way. When they reach a cadaver, females immediately begin to nest and deposit eggs into the body through its orifices: the nostrils, ear canals and mouth. Their behaviour is quite variable, though — if the ambient temperature changes, their lifetime is considerably affected.

Knowing how temperature affects blow-flies is tremendously significant within forensic entomology: an unusual life cycle might indicate a body’s movement or tampering.


2. Hard-bodied beetles

Those tiny, shiny critters in your back garden? They’re some of the largest creatures that will come into contact with a human cadaver, and arrive soon after the body begins to putrefy. Unlike flies which make do with extracting semi-liquid material from a corpse, beetles actually have chewing mouth-parts which allows them to manage tougher foods, and allows them to directly consume tissue (making the cadaver a veritable feast).

Three types of beetles are involved in this process: early arrivals tend to be predators that feed on fly larvae (the first colonizer, as described above); the late arrivals tend to feed on skin and tendons as the body slowly dries up; and finally, there are beetles with more variable diets which may eat either larvae or tissues.


3. Mitey moths.

Mites and moths are also involved in human decomposition — they’re not just parasites eating your woolen clothing, or snoozing in your bed. Strangely enough, mites belong to the same group as spiders, scorpions and harvestmen — so they’re technically not insects. Thousands of mites feed on a corpse during decomposition; and have a mutually beneficial relationship with carrior beetles. Moths, those sinister-looking zombie butterflies, feed on mammalian hair while they’re larvae.


4. Wasps, ants and bees, OH MY!

It’s worth mentioning that several other insect types — including parasitic wasps — lay their eggs inside the larvae or pupae of flies, and are as such, known as parasitoids. Wasp eggs (hold onto your lunch!) hatch inside these maggots — after which they eat it from the inside out, and kill it in the process. Wasps and bees have also been known to consume human tissue during early stages although they’re not necessarily considered scavengers.


Your Turn: Feeling a bit too nauseous for that sandwich now and think this article needs a warning? Know of any other little critters we’ve missed here, or have some intriguing entomological trivia to share? Let us know in the comments. We’d like to hear from you.



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