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Eeew! Maggot Mass Temperature

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If you're looking for an experiment that will gross out just about everyone, you probably can't do much better than this! This project investigates an important question in the field of forensic entomology. Just make sure to get permission at home before you start.


Areas of Science
Time Required
Very Long (1+ months)
This project requires an Investigator who is not squeamish, and who is able to secure parental support for a project involving primary decomposers.
Material Availability
Specialty items
Low ($20 - $50)
Disinfect containers with 5% bleach solution before disposal.

Andrew Olson, Ph.D., Science Buddies


This project is based on:


The goal of this project is to determine if maggot mass temperature increases as the number of maggots in the mass is increased.


This project is not for those that are easily grossed out. If this is you, just hit the back button on your browser before reading further, and you'll be fine. If you aren't squeamish, and you think you might be interested in doing a project related to forensic entomology, then keep on reading.

"Forensic entomology is the study of insects and other arthropods in a legal context. The applications are wide-ranging, but the most frequent is to determine the minimum time since death (minimum post-mortem interval, or PMI) in suspicious death investigations. This is done by identifying the age of the insects present on a human corpse, which can provide a relatively precise estimate in circumstances where pathologists may only be able to give a broad approximation. The fundamental assumption is that the body has not been dead for longer than it took the insects to arrive at the corpse and develop. Thus, the age of the oldest insects on the body determines the minimum PMI." (Hall and Brandt, 2006)

All insects start out life as eggs, although some hatch within the body of the mother, who then seeks out a source of food on which to deposit the living larvae (fly larvae are also called maggots). The flesh flies (scientific name Sarcophaga bullata) you will use in this project are an example of this type of insect. Blow flies (family Calliphoridae) are the usual "pioneer" species on an exposed animal corpse. Flesh flies generally arrive a day later. However, since flesh flies are deposited as larvae, and blow fly eggs take about 24 hours to hatch, the flesh fly maggots can develop as quickly as the blow fly maggots (Major, 2003).

As young insects grow and develop, their bodies change in a process called metamorphosis. In a few species, for example silverfish, only size changes. In other species, there is a simple change—development of wings in grasshoppers, for example. In other insect species, such as flies, there is a complete metamorphosis from the larval stage to the adult body form. (Borror and White, 1970; Illinois DNR, 2003)

Photo of a flies lifecycle starting from eggs, then three stages of larvae, pupae and finally adult flies
Figure 1. This photograph shows the stages of the fly life cycle. Shown are (clockwise, from lower left) adults, eggs, first instar larvae, second instar larvae, third instar larvae, pupae. (Hall and Brandt, 2006)

Insect larvae pass through multiple stages of growth, called instars. Because insects must shed their exoskeleton in order to grow, each growth stage is separated by a molt (also called ecdysis). As shown in Figure 1 (above), fly larvae pass through three instar stages (two molts). At the end of the third instar stage, the maggots disperse, seeking a location in soil before pupation. Pupae are inactive, and do not feed. Adults emerge from the puparium in one to two weeks at room temperature (Figure 2, below). Pupae can hibernate for long periods during colder temperatures, allowing flies to overwinter in the pupal stage and to emerge as adults in warmer spring weather.

Photo of a fly emerging from a pupae
Figure 2. An adult fly emerging from a pupa.

Development of fly larvae can be strongly dependent on temperature. Figure 3 (below) shows the total development time for blue bottle blow flies, from egg-laying to emergence of adults (in days), as a function of ambient temperature (in °C). You can see that over the range from 10 to about 17°C, each 1°C increase in temperature results in a significant decrease in development time.

Graph of the effect of temperature on the rate of fly development

A gradual negative sloping graph shows that as temperature increases the days required for a fly to reach adulthood decreases exponentially.

Figure 3. Effect of temperature on development of blue bottle blow flies. (Hall and Brandt, 2006)

Flies lay eggs and larvae in clumps, and the developing maggots mass together as they grow. The individuals benefit from shared secretions which aid in digestion and produce an alkaline environment conducive to larval growth. "The larval infestations might look gruesome, but they are a vital component of the natural recycling of organic matter and, on human bodies, they can provide vital clues to the timing and cause of death." (Hall and Brandt, 2006) The mass of maggots can also cause a local increase in temperature. The goal of this project is to determine whether maggot mass temperature increases as the number of maggots in the mass increases. A more advanced project (see the Variations section, below) would also try to determine if increasing maggot mass can lead to decrease in development time, and, if so, over what temperature range.

Terms and Concepts

To do this project, you should do research that enables you to understand the following terms and concepts:

More advanced students should also study:


More advanced students should also study:


Here is an introduction to forensic entomology by two scientists from The Natural History Museum in London, England. Please note: This site contains strong graphic images and descriptions.
  • Hall, M. and A. Brandt. (2006). Forensic Entomology. Science in School. Retrieved August 29, 2006.
What happens to an animal's body after death? This webpage on decomposition and the insects involved has the answers. Please note: this site contains strong graphic images and descriptions. These webpages contain information on flesh flies and their life cycle. Please note: The Australian Museum website contains strong graphic images and description. This website has descriptions and calculators for several statistical tests, including the Student's t-test that you can use in this project:
  • Kirkman, T. (n.d.). Student's t-Tests. Department of Physics, College of St. Benedict & St. John's University. Retrieved February 23, 2006.

Materials and Equipment

To do this experiment you will need the following materials and equipment:

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Experimental Procedure

  1. Do your background research and make sure that you are knowledgeable about the terms, concepts, and questions, above.
  2. You wll need to plan ahead for this experiment. You need to allow time for ordering the pupae, and then for emergence of the adults and development of the larvae. Remember that it will take about 1 to 2 weeks for the adult flies to emerge from the pupae, and then two or three days more for the adults to mate and lay larvae. It will take a further two days for the larvae to mature to the third instar state which you will use in this study. Note that there is a degree of uncertainty in the development times. Once you receive the larvae, it could be as few as 9 or as many as 16 days until you have third instar larvae to study.
  3. Forewarned is forearmed: "We also discovered that the smell of rotting beef liver leaves a significant trace of bad odor long after the completion of an experiment." (Kouyoumdjian, 2006) You'll want to think carefully about the best place to conduct your experiment. To simplify the interpretation of your data, it would be best to have a stable ambient temperature. However, this is a smelly experiment, and we don't recommend doing this inside your house.
  4. Keep pupae at constant temperature in enclosed container with air holes. Adult flies will emerge in 1 to 2 weeks.
  5. When the flies emerge, provide them with pieces of beef liver. The adults will feed on the liver, mate, and lay larvae. The larvae will feed on the decaying liver. Make sure your container excludes outside insects from entering.
  6. The larvae will molt twice (about one day of growth for each molt).
  7. After the second molt you will have third instar larvae. Put on gloves and separate the larvae into several different mass sizes: 25, 50, 100, 200, 400. (We told you this project was not for the squeamish!) Put each mass in its own container, each with its own piece of liver.
  8. Keep the containers at the same ambient temperature.
  9. Monitor the ambient temperature and the internal temperature of each maggot mass regularly (every 1–2 hours). For each measurement of maggot mass temperature, take several readings at different places within the mass. Record each location and temperature.
  10. For each time point, calculate the average and standard deviation of the temperature measurements for each maggot mass.
  11. More advanced students should use Student's t-test to determine whether any differences in average maggot mass temperature are statistically significant.
  12. Wear gloves for cleanup. Seal the decomposing liver and remaining larvae and pupae in a 2–3 layers of plastic bags for trash pickup. Disinfect the containers with a 5% solution of household bleach in water before disposal.
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Ask an Expert

Do you have specific questions about your science project? Our team of volunteer scientists can help. Our Experts won't do the work for you, but they will make suggestions, offer guidance, and help you troubleshoot.


  • For an alternative (and less smelly!) experiment on temperature and insect development, see the Science Buddies project: Does Temperature Affect the Rate of Butterfly Development?
  • Extend the experiment to earlier stages of development. Separate first instar larvae into different mass sizes and take regular temperature measurements. Does increased maggot mass lead to increased temperature for the first and second instar stages?
  • Does increased maggot mass lead to a decrease in development time? Design an experiment to find out. Study the temperature dependence of fly development carefully, and select three different ambient temperatures to test.


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MLA Style

Science Buddies Staff. "Eeew! Maggot Mass Temperature." Science Buddies, 20 Nov. 2020, https://www.sciencebuddies.org/science-fair-projects/project-ideas/Zoo_p023/zoology/maggot-mass-temperature. Accessed 25 Sep. 2023.

APA Style

Science Buddies Staff. (2020, November 20). Eeew! Maggot Mass Temperature. Retrieved from https://www.sciencebuddies.org/science-fair-projects/project-ideas/Zoo_p023/zoology/maggot-mass-temperature

Last edit date: 2020-11-20
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