PHASE 1 : Background Information
Insects can be used to estimate the post-mortem interval by identifying how long a person has been dead. There are many types of insects used in forensic entomology. Some types include blow flies, ants, bees, wasps, moths, mites, and beetles. The stages of life a blow fly will go through are eggs, larva , pre-pupa, early and late pupa, and finally the adult stage.
Forensic entomology is reliable because it tells entomologist what they need to know about the time of the death.
PHASE 2: Write your hypothesis
The book claims that each stage of life will last 8 hours for eggs, 20 hours for Larva 1, 15-20 hours for Larva 2, 36-56 hours for Larva 3, 86-180 for Pre-Pupa, 6-12 days for Early and late Pupa, and 3 weeks for Adult phase. I think that the blowflies in our experiment will go through their life cycle at the same rate as the textbook. I chose this hypothesis because it seems that it would take this long to develop all stages.
PHASE 3: Build your experimental apparatus
Apparatus from the first day:
We got a HEB plastic bakery container, and cut the top off with scissors. Then we wrapped the raw chicken in a piece of brown construction paper. It was built this way so that the blowflies could enter the container through the blue tub they were placed in and lay it’s eggs there. We also tried the brown construction paper to see how it would effect them by developing faster or slower instar and if there would be more pupa.
PHASE 4: Data Collection
Stage Size Color Stage& Time Weather Characteristic Picture
Day 0: N/A N/A 12:03pm 89 degrees Raw chicken
Day 5: .7 cm Off white 12:45pm/ Larva 1 87 degrees Spikes
Day 7: 1 cm Light tan 12:10pm/ Larva 2 84 degrees Tan,spikes
Day 9: .7 cm Dark Brown 12:13pm/Pupae 84 degrees It rained, spikes
Day 14: Adult fly Green, blue, black 12:37pm/ Adult 84 degrees Greenbottle Fly
Since flies will continue to enter the container and lay new eggs we can account for this by taking the oldest pupa out the container and compare it with the smallest.
PHASE 5: Interpret and analyze your data
In conclusion, the textbook was not accurate due to the fact that my group was one of the groups that had the brown construction paper, our pupa became adults at a faster rate. My hypothesis was that the blowflies would go through their life cycle at the same rate as the textbook. My hypothesis was incorrect. We noticed that because our raw chicken was wrapped in the brown construction paper, flies were able to lay their eggs there a lot faster then the other containers without the paper. Next time we could test the different times of the eggs being layed with different papers around the chicken to see how it would change the life cycle rate. I’ve learned from this experiment that forensic entomology is sometimes very reliable, and sometimes not so reliable depending on different factors.