Week 2: 2-3 June 2007: Huge Maggot Exodus

An incredible sequence of maggot migration...

3 June 2007: Rain has created a situation where maggots are creating large amounts of 'froth' around the edge of the bear.

3 June 2007: Maggots are moving in an enormous exodus from the bear. We began to see this to a smaller degree several days ago, but now they are grouping together in a virtual maggot swarm.

3 June 2007: A close-up of maggots on the trail...

3 June 2007: A maggot's-eye view of the exodus of the carcass. The maggots remaining on the bear are probably somewhat younger. Many early instars of blow flies are still present on the carcass. There will probably be another substantial mass movement of maggots of the carcass in upcoming days.

3 June 2007: During the study, we have been keeping track of maggot development. At the bottom is a mature maggot. Above that is a newly formed pupa (hours old), followed by a darker puparium a day or so old, followed by progressively darker (and older) puparia.

2 June 2007: In the morning, many maggots are mature and actively moving. This appears to be in preparation for a mass migration off the carcass. The stench is still horrendous, and the vegetation is dying around the bear.

2 June 2007: The first real "wave" of maggots leaving the carcass. Many maggots continue to grow an develop on the carcass. Adult flies (Calliphoridae, Muscidae, Sepsidae, Piophilidae) are still active on and around the bear.

2 June 2007: A maggot's- eye view of the trail...

Black Bear Decomposition and Wildlife Poaching: How Insects Help Investigations

The poaching of wildlife is an age-old problem that continues today. Black bear are harvested for meat, and their gall bladders are taken for their use in creating traditional medicines. The species is endangered in Ohio, and it is illegal to harvest them.

To date, data are lacking on the use of insects to determine the approximate time of death of a poached animal. The use of forensic entomology has been used extensively to assist in human death under mysterious or suspicious circumstances (See the Cleveland Museum of Natural History’s Forensic Entomology web site:

http://www.cmnh.org/site/ResearchandCollections_InvertebrateZoology_Research_ForensicEnt.aspx).

By collecting insects and determining how old they are, investigators can estimate the approximate (or more accurately the minimum) time of death. Blow flies are the most important visitor at carcasses (or human bodies) because of their sensitive sense of smell. They can find bodies/carcasses exposed to nature within minutes or just a few short hours following death and begin to lay eggs immediately. The eggs hatch, and the larvae feed and grow. The trained entomologist is able to age the maggots and therefore judge the approximate time of first egg-laying, thus determining the time between death and body discovery, or postmortem interval. Note that blow flies will not lay eggs on living tissue except under very rare circumstances.

The Cleveland Museum of Natural History acquired a black bear struck by a car in Ashtabula County some 10 years ago. It can not be taxidermied, so the bear will be used as a foresnic wildlife study subject. The specimen will be placed out at an undisclosed (for security purposes) site in Geauga County, Ohio, and left to the insect scavengers who will “recycle” the bear carcass back to nature. At the conclusion of our observations, the bones will be collected and placed in the Museum’s osteology (bone) collection.

Soon after the bear is placed in nature, pigs will be placed out cotangentially for comparative purposes. Because of their percent hair cover on the body, size, and volume of body cavity is similar to humans, swine make fine substitutes for human cadavers during forensic entomology investigations.

We will upload text, photo, and video observations of this decomposition study throughout the summer.


Joe Keiper, Ph.D.
Curator of Invertebrate Zoology
Cleveland Museum of Natural History
16 May 2007