Climate Data & Calculations
Analysis Tutorial

Degree-Hour Determination
A degree-hour is a unit of measure for charting insect growth. It is just an expression for the amount of time spent at a specific temperature.
For example, flies that are incubated at 90 degrees for one hour will have the same level of development as those that are kept at 45 degrees for two hours.
90 degrees * 1 hour = 90 degree-hours
45 degrees * 2 hours = 90 degree-hours
30 degrees * 3 hours = 90 degree-hours

Actual Lab data
Adult Woman in Cabin Adult Man in Cabin
Eggs
1 st Instar
2 nd Instar
3 rd
Feeding
3 rd
Migrating
Pre-Pupae
Pupae
Adult
Species A Species B
1
1
2
2
3
2
Eggs
1 st Instar
2 nd Instar
3 rd
Feeding
3 rd
Migrating
Pre-Pupae
Pupae
Adult
Species A Species B
5
3
1
3 1
2
4
4 1
3 rd Instar Migrating were the most developed larvae from Species A and 2 nd Instar were the most developed from Species B. The adult flies from each species represent those laying eggs
NOT adults resulting from a full life cycle.

Degree-Hour Determination
Knowns
• Bodies discovered at 1:00PM on June 20
• Insects collected at 3:00PM on June 20
• Weather type (sunny, partly cloudy, overcast)
• Weather events (rain, thunderstorms, snow)
• Daily average temperature
• Male and Female had the same species and lifecycles present
(Migrating 3 rd Instar Species A, 2 nd Instar Species B)
Unknowns
• Elapsed degree-hours for each day
• Degree-hours for each life stage of both species
• Cumulative degree-hours for each life stage of both species
• Average Temperature for the month of June
• Which day the adult insect from both species laid its eggs (PMI)
• Earliest and latest time the insects began developing

Elapsed degree-hours for each day
Lab Procedure 2, Step 2: Determine the number of degree hours for each day using the weather service data. To do this, multiply the average temperature times 24 hours for each day. This can be performed in a spreadsheet.
• Every daily average temperature in the month will be multiplied by 24 except June 20.
• The collection time was 3:00PM on June 20, this tells us to multiply the average temperature on this day by 15 hours
(12:00AM through 3:00PM = 15hrs) instead of
24 hours

Elapsed degree-hours for each day
COOLING DAY AVG DEPARDEPAR-TURE
TURE FROM FROM NORMAL
NORMAL
HEATING TOTAL
WATER
EQUIV
SNOW-FALL,
ICE PELLETS
SNOW, ICE
PELLETS OR ICE
ON GROUND
AVG
SPEED
(MPH)
AVG
SPEED
(KPH)
SKY COVER
SUNRISE-
SUNSET
WEATHER
OCCURENCES
PEAK
WIND (KPH) degree hours
12.4
12.6
14.7
14.5
13.2
13.1
14.2
10.7
11.5
12.8
12.7
12.9
12.7
12.8
12.9
13.2
12.5
12.8
12.5
13.2
9
10
11
12
13
14
6
7
8
15
16
17
18
19
20
1
2
3
4
5
2.6
1.4
-1.9
0.9
-1.9
-2.7
-7.5
-5.9
-3.0
-5.2
-4.7
-5.1
-1.6
-2.1
0.4
-1.9
-3.0
-5.2
-4.7
1.4
1.4
0.8
-1.0
0.5
-1.0
-1.5
-4.2
-3.3
-1.7
-2.9
-2.6
-2.8
-0.9
-1.2
0.2
-1.0
-1.7
-2.9
-2.6
0.8
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
2.2
3.3
5.6
5.0
0.0
0.00
0.07
0.11
0.00
0.00
0.67
1.13
0.23
0.02
T
0.00
0.00
0.00
0.00
0.00
0.00
0.09
0.19
0.28
0.00
0.6
0.0
0.0
0.0
0.0
0.0
2.2
1.1
0.0
0.0
0.0
0.0
0.0
2.8
5.0
0.0
0.0
0.0
0.0
1.1
0
T
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
12.96
10.08
21.12
6.72
14.208
31.36
37.6
22.72
16.8
19.04
10.24
15.2
17.76
7.36
11.84
10.08
22.08
27.52
19.68
17.76
8.1
6.3
13.2
4.2
8.88
19.6
23.5
14.2
10.5
11.9
6.4
9.5
11.1
4.6
7.4
6.3
13.8
17.2
12.3
11.1
6
8
7
8
3
6
6
8
8
3
2
1
1
4
3
6
6
8
9
7
3,5
1,3,5
1,2
1
0
0
0
0
0
0
0
0
0
0
0
1
1,2
0
0
5
386.666667
360
306.666667
320
466.666667
493.333333
466.666667
386.666667
453.333333
386.666667
367.2
252
290.4
360
306.666667
320
309.6
393.6
381.6
276
S 18.7
SE 26.2
SW 33.3
W 38.6
W 28.3
SW 24.3
S 16.7
S 27.9
SE 10.3
S 22.7
S 32.4
SW 43.8
S 29.8
S 24.5
SW 23
W 19.2
S 27.2
W 26.3
SW 17.8
W 23.1

Degree-Hour Determination
Knowns
• Bodies discovered at 1:00PM on June 20
• Insects collected at 3:00PM on June 20
• Weather type (sunny, partly cloudy, overcast)
• Weather events (rain, thunderstorms, snow)
• Daily average temperature
• Male and Female had the same species and lifecycles present
(Migrating 3 rd Instar Species A, 2 nd Instar Species B)
Unknowns
• Elapsed degree-hours for each day
• Degree-hours for each life stage of both species
• Cumulative degree-hours for each life stage of both species
• Average Temperature for the month of June
• Which day the adult insect from both species laid its eggs (PMI)
• Earliest and latest time the insects began developing

Degree-hours for each life stage: Species A
Lab Procedure 2, Step 3: Determine the number of degree-hours required for each life stage of both species. To do this, multiply the number of hours by the degrees Celsius given in the life cycle table.
Temp
°C
21
Egg
21 hrs
21 hrs *21˚C
= 441 deg-hrs
1 st Instar 2 nd Instar Feeding 3 rd
Instar
31 hrs
31*21 =
651
26 hrs
26*21 =
546
50 hrs
50*21 =
1050
Migrating
3 rd Instar
118 hrs
118*21 =
2478
Pupa
240 hrs
240*21 =
5040

Degree-hours for each life stage: Species B
Lab Procedure 2, Step 3: Determine the number of degree hours required for each life stage of both species. To do this, multiply the number of hours by the degrees Celsius given in the table.
Temp
°C
Egg 1 st Instar 2 nd Instar Feeding 3 rd
Instar
Migrating
3 rd Instar
Pupa
21 25 hrs
25*21 =
525
37 hrs
37*21 =
777
31 hrs
31*21 =
651
60 hrs
60*21 =
1260
124 hrs
124*21 =
2604
286 hrs
286*21 =
6006

Degree-Hour Determination
Knowns
• Bodies discovered at 1:00PM on June 20
• Insects collected at 3:00PM on June 20
• Weather type (sunny, partly cloudy, overcast)
• Weather events (rain, thunderstorms, snow)
• Daily average temperature
• Male and Female had the same species and lifecycles present
(Migrating 3 rd Instar Species A, 2 nd Instar Species B)
Unknowns
• Elapsed degree-hours for each day
• Degree-hours for each life stage of both species
• Cumulative degree-hours for each life stage of both species
• Average Temperature for the month of June
• Which day the adult insect from both species laid its eggs (PMI)
• Earliest and latest time the insects began developing

Cumulative degree-hours for each life stage:
Species A
Lab Procedure 2, Step 4: By adding all the degree hours for each of the six life stages together, you calculate the cumulative degree hours required for an adult fly to develop at 21 ° C.
Temp °C Egg 1 st Instar 2 nd Instar Feeding 3 rd
Instar
21 21 31 26 50
546 1050 Deg Hrs 441 651
Cum.
Deg Hrs
441
Migrating
3 rd Instar
118
2478
Pupa
240
5040

Cumulative degree-hours for each life stage:
Species A
Lab Procedure 2, Step 4: By adding all the degree hours for each of the six life stages together, you calculate the cumulative degree hours required for an adult fly to develop at 21 ° C.
Temp °C Egg 1 st Instar 2 nd Instar Feeding 3 rd
Instar
21 21 31 26 50
546 1050 Deg Hrs 441 651
Cum.
Deg Hrs
441 651+441
= 1092
Migrating
3 rd Instar
118
2478
Pupa
240
5040

Cumulative degree-hours for each life stage:
Species A
Lab Procedure 2, Step 4: By adding all the degree hours for each of the six life stages together, you calculate the cumulative degree hours required for an adult fly to develop at 21 ° C.
Temp °C Egg 1 st Instar 2 nd Instar Feeding 3 rd
Instar
21 21 31 26 50
1050 Deg Hrs 441 651
Cum.
Deg Hrs
441 651+441
= 1092
546
546+1092
= 1638
Migrating
3 rd Instar
118
2478
Pupa
240
5040

Cumulative degree-hours for each life stage:
Species A
Lab Procedure 2, Step 4: By adding all the degree hours for each of the six life stages together, you calculate the cumulative degree hours required for an adult fly to develop at 21 ° C.
Temp °C Egg 1 st Instar 2 nd Instar Feeding 3 rd
Instar
21 21 31 26 50
Deg Hrs 441 651
Cum.
Deg Hrs
441 651+441
= 1092
546
546+1092
= 1638
1050
1050+1638
= 2688
Migrating
3 rd Instar
118
2478
Pupa
240
5040

Cumulative degree-hours for each life stage:
Species A
Lab Procedure 2, Step 4: By adding all the degree hours for each of the six life stages together, you calculate the cumulative degree hours required for an adult fly to develop at 21 ° C.
Temp °C Egg 1 st Instar 2 nd Instar Feeding 3 rd
Instar
21 21 31 26 50
Deg Hrs 441 651
Cum.
Deg Hrs
441 651+441
= 1092
546
546+1092
= 1638
1050
1050+1638
= 2688
Migrating
3 rd Instar
118
2478
2478+2688
= 5166
Pupa
240
5040

Cumulative degree-hours for each life stage:
Species A
Lab Procedure 2, Step 4: By adding all the degree hours for each of the six life stages together, you calculate the cumulative degree hours required for an adult fly to develop at 21 ° C.
Temp °C Egg 1 st Instar 2 nd Instar Feeding 3 rd
Instar
21 21 31 26 50
Deg Hrs 441 651
Cum.
Deg Hrs
441 651+441
= 1092
546
546+1092
= 1638
1050
1050+1638
= 2688
Migrating
3 rd Instar
118
2478
2478+2688
= 5166
Pupa
240
5040
5040+5166
= 10206

Cumulative degree-hours for each life stage:
Species A
Lab Procedure 2, Step 4: By adding all the degree hours for each of the six life stages together, you calculate the Accumulated degree hours required for an adult fly to develop at 21 ° C.
Temp °C Egg 1 st Instar 2 nd Instar Feeding 3 rd
Instar
21 21 31 26 50
Deg Hrs 441 651
Accum.
Deg Hrs
(ADH)
441 651+441
= 1092
546
546+1092
= 1638
1050
1050+1638
= 2688
Migrating
3 rd Instar
118
2478
2478+2688
= 5166
Pupa
240
5040
5040+5166
= 10206
Accumulated degree-hours (ADH) = Sum of degree hours at each stage
= 10206

Now we will repeat the Accumulated degree-hours calculation for Species B

Cumulative degree-hours for each life stage:
Species B
Lab Procedure 2, Step 4: By adding all the degree hours for each of the six life stages together, you calculate the Accumulated degree hours required for an adult fly to develop at 21 ° C.
Temp °C Egg 1 st Instar 2 nd Instar Feeding 3 rd
Instar
21 25 37 31 60
Deg Hrs 525 777
Accum.
Deg Hrs
(ADH)
525 777+525
= 1302
651
651+1302
= 1953
1260
1260+1953
= 3213
Migrating
3 rd Instar
124
2604
2604+3213
= 5817
Pupa
286
6006
6006+5817
= 11823
Accumulated degree-hours (ADH) = Sum of the degree hours at each stage
= 11823

Degree-Hour Determination
Knowns
• Bodies discovered at 1:00PM on June 20
• Insects collected at 3:00PM on June 20
• Weather type (sunny, partly cloudy, overcast)
• Weather events (rain, thunderstorms, snow)
• Daily average temperature
• Male and Female had the same species and lifecycles present
(Migrating 3 rd Instar Species A, 2 nd Instar Species B)
Unknowns
• Elapsed degree-hours for each day
• Degree-hours for each life stage of both species
• Accumulative degree-hours for each life stage of both species
• Average Temperature for the month of June
• Which day the adult insect from both species laid its eggs (PMI)
• Earliest and latest time the insects began developing

Elapsed degree-hours for each day
DAY AVG
12.4
12.6
14.7
14.5
13.2
13.1
14.2
10.7
11.5
12.8
12.7
12.9
12.7
12.8
12.9
13.2
12.5
12.8
12.5
13.2
9
10
11
12
13
14
6
7
8
15
16
17
18
19
20
1
2
3
4
5
Average temp for the month = 12.9◦C

Degree-Hour Determination
Knowns
• Bodies discovered at 1:00PM on June 20
• Insects collected at 3:00PM on June 20
• Weather type (sunny, partly cloudy, overcast)
• Weather events (rain, thunderstorms, snow)
• Daily average temperature
• Male and Female had the same species and lifecycles present
(Migrating 3 rd Instar Species A, 2 nd Instar Species B)
Unknowns
• Elapsed degree-hours for each day
• Degree-hours for each life stage of both species
• Cumulative degree-hours for each life stage of both species
• Average Temperature for the month of June
• Which day the adult insect from both species laid its eggs
• Earliest and latest time the insects began developing

Calculating the PMI
Post Mortem Interval = ADH/Average actual temp
= 2688/12.9
Use the ADH from the Feeding
3 rd Instar – species A because
= 208 hours (divide by 24)
= 8.68 days (multiply .68*24 for hours)
= 8 days, 15 hours that is the maximum amount of time needed
(the ADH for 2 nd Instar – species B is only 1302 hrs)

Conclusion: Bodies have been dead for a minimum of 8 days, 16 hours
DAY degree hours Post Mortem Interval = 8 days, 15 hours
9
10
11
12
13
14
15
16
17
18
19
20
453.333333
386.666667
367.2
252
290.4
360
306.666667
320
309.6
393.6
381.6
276
THUNDERSTORM
The post mortem interval was calculated to be 8 days, 16 hours, but we know that the storm occurred on the evening of the 11 th , so we conjecture that the flies were active at least an hour on the 11 th to give them time to lay the eggs, thus bringing our PMI to a minimum of 8 days,
16 hours . The actual PMI, which is unknown, may vary up to 12 hours more than this calculation due to weather.
Students’ calculations may vary by up to a day later.