Insect Timing and Succession
on Buried Carrion in East
Lansing, Michigan
Emily Pastula
and Richard W. Merritt
Department of Entomology
Michigan State University
East Lansing, MI
Introduction
• In the criminal world, burial is a popular
disposal technique.
• Assailants tend not dig very deep, generally
less than 3 feet
– Time
– Effort
– Longer in contact with the body,
more likely to get caught
Previous Studies
• Payne and King (1968) buried baby pigs and
determined 26 of 48 arthropod species found were not
associated with above ground carrion.
• In 1985 Rodriguez and Bass studied decomposition
rates on six human cadavers and found carrion insects
on those buried at one foot, while the two foot and
four foot cadavers showed no activity.
– Witnessed that on days following heavy rain, female flies
would lay their eggs on the soil surface allowing the larvae
to migrate down to the carcasses through the cracks in the
soil.
• VanLaerhoven and Anderson established an insect
succession database for each stage of decomposition
of a carcass buried at one foot in British Columbia in
1999.
Objectives
1. Determine if insects can
colonize a carcass buried
at a depth of two feet.
2. Examine how long it
takes insects to colonize
a carcass buried at one
and two foot.
3. Examine what fauna are
present at these two
depths at different time
intervals.
Location
Soil Analysis
Sample %
%
ID
Sand % Silt Clay
NL 1
52.6 26.7 20.7
NR 2
45.3
32
22.7
C3
57.3
18
24.7
SL 4
53.3
24
SR 5
51.3
28
Soil Type % OM
Sandy Clay
Loam
2.5
22.7
Loam
Sandy Clay
Loam
Sandy Clay
Loam
2.8
20.7
Loam
3
1
2
2.8
3
4.6
4
5
Depths
Studying two
different depths
– One foot and two
feet
– Bottom of hole
measures the depth
– 4 controls on
surface for insect
comparison
1
2
3
4
2ft
1ft
1ft
2ft
2 Control
1ft
1ft
2ft
3
2ft
1ft
2ft
2ft
4
2ft
1ft
Control
1ft
5
1ft
2ft
2ft
1ft
1
N
6
1ft
2ft
1ft
2ft
7
2ft
2ft
2ft
1ft
8
2ft
Control
1ft
1ft
9
2ft
1ft
2ft
1ft
10
2ft
1ft
Control
11
2ft
2ft
1ft
Timing
• Increased frequency
of sampling
• Seven exhumation
intervals
– 3 days, 5 days,
7 days, 2 weeks,
3 weeks, 1 month,
and 2 months
– Two pigs left at 2ft
one for 3 months and
one for 4 months
1
2
3
4
5
6
7
8
9
10
11
1
4mo
A
Control
A
1mo
B
7days
A
2weeks
B
5days
A
3weeks
C
2weeks
B
2mo
B
2
3
4
3weeks 1mo 3weeks
A
A
A
3days
7days
1mo
A
A
A
2weeks 3days 2weeks
A
A
A
3weeks Control
2mo
B
B
A
2mo
5days
7days
A
A
B
3weeks 2mo
1mo
B
B
C
7days
3mo
1mo
B
A
B
Control 5days 2weeks
C
B
C
7days
5days 3weeks
C
B
C
7days
1mo
Control
C
C
D
2weeks 2mo
2mo
C
C
C
Pigs
• 38 total buried, 3 pigs
at each depth per
time interval, plus 4
controls = 42 pigs
• 30 to 60 pounds
• Killed via lethal
injection directly into
heart using Fatal Plus
– Morning of burial
– Double bagged
Controls
Exhumation
Exhumation
• Once pig exposed,
brought to surface
• Collection starts at
head and move
towards rear
• 15 minutes per pig
allotted for collection
once pig on surface
Results
How long does it take
insects to colonize a carcass
buried at one foot?
5 days! Hydrotaea spp.
(Muscidae) & Sarcophaga
bullata
Results
What fauna are present at one foot at different
time intervals?
1 Foot Grave Species Presence
Megaselia scalaris
Phormia regina
Sarcophaga bullata
Hydrotaea ignava
Hydrotaea spp. 2
Hydrotaea spp. 1
+
+
5
+
+
+
7
+
+
+
+
+
+
14
21
Time (Days)
+
+
+
+
30
+
+
60
Results
Can insects colonize a
carcass buried at a depth
of two feet?
YES! They can!
How long does it take
insects to colonize a
carcass at two feet?
7 days! Megaselia scalaris
(Phoridae) & Hydrotaea
spp. (Muscidae)
Results
What fauna are present at two feet at different
time intervals?
2 Foot Grave Species Presence
Megaselia scalaris
Hydrotaea spp. 1
+
+
7
+
14
+
+
21
30
Time (Days)
60
+
90
Conclusions & Further Study
• There is a difference in fauna present at these two
depths.
• Sarcophaga bullata is the dominate species on 1ft
carcasses.
– Could soil type be playing a role in the different species
present?
• Megaselia scalaris is the dominate species on 2ft
carcasses.
– Could be an indicator species to determine the elapsed time
since death. Need developmental rates and temperature data.
My Future Work
• Calculate degree days
from temperature
collected by
temperature loggers.
• Determine species
richness, evenness,
and diversity.
• Develop a maturity
index.
Acknowledgements
• Committee: Drs. Rich Merritt,
Michael Kaufman, and Todd
Fenton
• Funding: Graduate School,
Michigan State University
• Guidance: Drs. Mollie McIntosh,
Ryan Kimbirauskas, Sherah
VanLaerhoven, George Bird,
Gregory Dahlem
• Field help: Emily Campbell, Olivia
Hudson, Thomas Pastula, and
Deborah Pastula
• Pigs: Al Snedegar and crew at the
Swine Teaching and Research
Center
• Machinery: Tony Boughton and
crew at University Farms
Questions?