Overview

     Forensic entomology is the scientific study of insects and other arthropods, and their application to legal investigations. This specialized field plays a crucial role in providing crucial evidence and insights that can help determine the cause and circumstances of death in criminal cases.

     Before getting into the details about finding the time of death using bugs, it is important to note that environmental conditions, type of insect, and many other factors can insect the timeline of development and therefore impact the estimated time of death. For HOSA, it is also important to note, that they rarely use entomology within round 2, but questions are often asked about it in round 1.

Collecting Insect Evidence at the Crime Scene
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When arriving at a crime scene, the forensic entomologist will:
- Record the number and types of adult and immature insects within 3-6 meters of the body.
- Note the surrounding habitat type, as this can suggest which insects to expect in that environment.
- Document the body's exact position, exposure to light, and the time of day.
- Observe any unusual phenomena that could affect insect activity, such as burial, trauma, or the presence of drugs.

Insects Found on the Body

     The first insects to arrive at a dead body are usually blowflies (Calliphoridae), attracted by body fluids and gases. Blowflies lay their eggs within two days after death, so the stage of their development - egg, larval stages, prepupal or pupal stage, or adulthood - can suggest how long the corpse has been undiscovered.
     As the body decomposes due to microbial fermentation, flesh flies (Sarcophagidae) are attracted to it. Later, the decomposition of body fat attracts hide beetles, and a Pyralid moth in the genus Aglossa might arrive. After three to six months, protein breakdown attracts other insects, such as the cheese skipper Piophila casei.
     Necrophagous species, or carrion feeders (mainly flies and beetles), actually consume the dead flesh. Other insects, like Rove Beetles (Staphylinidae), are predatory on the carrion feeders. Among the beetles, the Dermestidae occur at the later stages of decomposition; then, when these turn up, members of the Histeridae may also arrive - these are predatory on Dermestidae larvae.

Unusual Insect Evidence

     If the insects found on the body are not those expected for the location, it could indicate that the body has been moved after death. Different blowfly species prefer different environments - warm or cool, urban or rural - so the presence of the "wrong" species could be suspicious.
     The insects found underneath the body will also vary with the length of time the body has been at the scene, providing more evidence of both time of death and whether the body may have been moved.
     In colder months, the presence of winter gnats (Trichoceridae) or the coffin-fly Conicera tibialis, associated with buried bodies, could suggest the body has been moved or disturbed.
     The presence of Coelopidae flies, which are found along the seashore, could indicate the body has lain on a beach.

Determining Time of Death

Forensic entomologists use two main methods to determine the time of death:

- Successional waves of insects: This method is used when the decedent has been dead for a few weeks up to a year or more. By analyzing the changing insect community on the body, the entomologist can establish a window of time in which death occurred.
- Maggot age and development: This method can provide a date of death accurate to a day or less, or a range of days, and is used in the first few weeks after death. By analyzing the stage of development of the earliest arriving insects, such as blowfly larvae, the entomologist can estimate the time since the insects first colonized the body, and thus the time of death.
- For our purposes, we are going to use a common blowfly life cycle timeline, but we advise that you do your own additional research since these timelines are so often disputed and argued upon.

          - Eggs - Within 24 hours of death
          - First Instar - Within 24 hours of the laying of the eggs
          - Second Instar - 24-28 hours
          - Third Instar - 47-51 hours
          - Pupae - After 132 hours
          - Adult fly - After 145 hours

Other Applications of Forensic Entomology

     Insect evidence can also reveal if a body has been moved to a secondary location after death, or if the body has been disturbed at some point. The presence of insects not native to the area where the body was found, or differences in the insect community between the body and the surrounding environment, can indicate the body was relocated.
     Forensic entomology can also provide information about the cause of death. The pattern of insect colonization can reveal the presence and location of wounds, while the analysis of insects found on the body can detect the presence of drugs or toxins that may have contributed to the individual's demise.
     In addition to criminal investigations, forensic entomology has applications in civil cases, such as determining the time of neglect or abuse in cases of child or elder mistreatment.

Limitations and Challenges

     While forensic entomology is a powerful tool, it does have some limitations. The accuracy of the time of death estimate depends on factors such as the availability of local insect population data, the ability to collect a complete insect sample, and the potential for the body to have been moved or disturbed.
     Additionally, certain methods of body disposal, such as freezing, burial, or wrapping, can exclude or delay insect colonization, making the entomological evidence less reliable. Ongoing research is aimed at addressing these challenges and expanding the applications of forensic entomology in death investigations.
     In conclusion, the meticulous collection and analysis of insect evidence by a trained forensic entomologist can provide crucial insights into the circumstances surrounding a person's death, including the time, location, and potentially the cause of death. This specialized field of forensic science continues to play an important role in supporting criminal investigations and legal proceedings.