Forensic Entomology: The Role of Insects in Criminal Investigations

Main Branches of Forensic Entomology

1. Medico-Legal Forensic Entomology

The most common branch.
Focuses on insects found on human remains to help:

• Estimate postmortem interval (PMI) – time since death

• Determine if a body was moved

• Identify neglect or abuse cases (especially in elderly or children)

2. Urban Forensic Entomology

Involves insect infestations in buildings.
Used in:

• Structural damage cases (e.g., termites)

• Pest disputes between tenants and landlords

3. Stored-Product Entomology

Deals with insects in food products.
Used in:

• Food contamination investigations

• Commercial disputes

How Insects Help Estimate Time of Death

When a person dies, the body begins to decompose and releases odors that attract insects — often within minutes.

Insect Succession (Order of Arrival)

1. Blowflies (Calliphoridae) – Arrive within minutes to hours; lay eggs.

2. Maggots (larvae) – Feed on tissues and grow rapidly.

3. Pupae – Develop into adult flies.

4. Beetles and other insects – Arrive during later decomposition stages.

By measuring:

• Species present

• Development stage

• Temperature (which affects growth rate)

Experts calculate how long insects have been developing, giving a reliable estimate of time since death.

Factors That Affect Insect Evidence

• Temperature (warmer = faster development)

• Burial or submersion

• Indoor vs outdoor location

• Season

• Drugs or toxins in the body

• Clothing or wrapping

Tools & Techniques Used

• Collection of eggs, larvae, pupae, and adults

• Rearing larvae to adulthood for species identification

• Microscopic examination

• DNA analysis

• Toxicological testing of maggots

• Temperature data analysis (degree-day calculations)

Importance in Criminal Cases

Forensic entomology is especially helpful when:

• The body is badly decomposed

• Soft tissues are destroyed

• Traditional autopsy methods cannot estimate time of death accurately

It can confirm or contradict alibis and sometimes reveal whether a body was moved after death.

Main Uses

• Estimating time of death (Postmortem Interval – PMI):
  By examining the life stages of insects (eggs, larvae, pupae, adults), experts can estimate how long a person has been deceased.

• Determining location of death:
  Certain insects are specific to particular environments (urban, forest, aquatic), helping identify whether a body was moved.

• Detecting wounds or trauma:
  Insects often lay eggs in open wounds, which may indicate injuries before death.

• Toxicology:
  Maggots feeding on a body can contain drugs or poisons present in the deceased.

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