Chapter 13 — Self-Check Quiz

24 questions: multiple choice and short answer. Try them closed-book. The answer key is in the collapsed block at the bottom.

Multiple choice

1. Forensic entomology most often estimates: - A. The exact time of death - B. The minimum time since death (a floor) - C. The cause of death - D. The identity of the killer

2. The first insects to colonize most exposed remains under warm conditions are: - A. Dermestid (hide) beetles - B. Mites - C. Blow flies (Calliphoridae) - D. Moths

3. "Accumulated degree days" captures: - A. The number of calendar days a body has been outdoors - B. The total heat over time available for insect development (degrees above threshold, summed) - C. The age of the victim in days - D. The temperature at the moment of death

4. Insects are ectotherms, which means: - A. They generate their own body heat at a constant rate - B. They develop at a rate set by the surrounding temperature - C. They cannot survive on dead tissue - D. They only colonize buried bodies

5. A day whose average temperature is below the species' developmental threshold contributes: - A. A negative number of degree-days - B. Zero degree-days - C. The threshold value in degree-days - D. Double degree-days

6. A large maggot mass that generates its own metabolic heat, if unaccounted for, tends to make a naive ambient-only PMI estimate: - A. Too long (an overestimate) - B. Too short (an underestimate) - C. Exactly right - D. Impossible to compute

7. Succession is most useful as a timekeeper for: - A. The first few hours after death - B. Longer intervals (weeks to months), after early colonizers have departed - C. Determining blood type - D. Identifying pollen

8. Live larvae are collected and reared to adulthood primarily to: - A. Keep them as pets - B. Confirm the species, since adults are far easier to identify than larvae - C. Speed up decomposition - D. Measure the victim's weight

9. A body found in a city alley bears larvae of a species that lives only in rural woodland. The most parsimonious inference is that: - A. The species is misidentified for certain - B. The body may have decomposed elsewhere and been moved (a primary-vs-secondary-scene question) - C. The time of death is exactly known - D. Pollen analysis is required to proceed

10. Palynology is the study of: - A. Insects on remains - B. Pollen and spores - C. Soil chemistry only - D. Bloodstain geometry

11. Pollen makes good trace evidence largely because: - A. It is rare and easily counted - B. It is produced in huge quantities, transfers invisibly, is very durable, and its assemblage reflects a place's plant community - C. It can be matched to one unique plant individual - D. It dissolves quickly, leaving a clean record

12. The honest forensic verb for a strong pollen-profile correspondence is usually: - A. "Proves the exact location" - B. "Individualizes the spot" - C. "Is consistent with / supports association with a place of that plant community" - D. "Identifies the suspect"

13. Entomotoxicology refers to: - A. The toxicity of insect bites - B. Analyzing arthropods to detect drugs/toxins in the tissue they consumed, and accounting for those substances' effects on development - C. Poisoning insects to preserve them - D. The study of pollen toxins

14. Fire at a death scene typically affects entomological estimates by: - A. Having no effect at all - B. Guaranteeing exact precision - C. Killing/repelling early colonizers and often delaying colonization, so the insect estimate may underestimate time since death - D. Speeding colonization so the estimate overestimates time since death

15. Compared to single-source nuclear DNA, accumulated-degree-day estimation is best described on the validity spectrum as: - A. Equally rigorous and quantified - B. Grounded in tested, reproducible physiology, yielding an interval with stated uncertainty — real science, but with noisier inputs and wider error than DNA - C. Fully discredited, like bite marks - D. Having no scientific basis

16. A pollen grain on a suspect's jacket might have come from the scene, the suspect's own backyard, or the air during the drive. This illustrates: - A. That pollen evidence is worthless - B. The transfer/persistence and background-"pollen-rain" problem, which requires control samples and expert judgment - C. That pollen individualizes locations - D. That entomology is more reliable than botany in all cases

17. In the cold case, the pollen on the vehicle floor mat most defensibly establishes: - A. Who was driving the vehicle - B. When the contact occurred - C. That the vehicle was at, or picked up material from, the cabin's distinctive environment - D. That a crime was committed

18. A precise entomological output such as "death occurred 9.7 days ago" is: - A. The gold-standard form of the result - B. A misuse — the honest output is an interval with stated assumptions, not a false-precision decimal - C. Required by law - D. More reliable than a range

Short answer

19. Explain, in two sentences, why the age of the oldest insects on a body gives a minimum PMI rather than the actual PMI.

20. Name three sources of error that compound in an accumulated-degree-day calculation, and for each, state in one phrase how it distorts the estimate.

21. Why does the distinctiveness of a pollen assemblage (e.g., a rare, localized species) increase the weight of a botanical association? Use a one-line analogy.

22. A detective gives the entomologist the "expected" date of death before analysis. State the bias risk and the safeguard (preview of Chapter 31).

23. In the cold case, explain how the autopsy finding of no soot in the airways (Chapter 11) is consistent with the §13.4 caution that fire can delay insect colonization.

24. Write one sentence an honest expert could say on the stand about the Mill Creek pollen evidence, and one sentence that would overstate it.

Answer key (click to expand) **Multiple choice:** 1-B · 2-C · 3-B · 4-B · 5-B · 6-A · 7-B · 8-B · 9-B · 10-B · 11-B · 12-C · 13-B · 14-C · 15-B · 16-B · 17-C · 18-B **Short answer (model points):** **19.** Blow flies start the insect "clock" only when they gain *access* to the tissue and begin developing; the oldest larvae therefore measure time *since colonization*, not time *since death*. If anything delayed colonization (cold, wrapping, a sealed space, fire, burial), the person was dead before the insects arrived — so the insect age is the *least* the person has been dead, a floor. **20.** Any three, e.g.: (a) **temperature reconstruction** — the scene's history is inferred from a weather station and a correction, and a microclimate can diverge, shifting the estimate either way; (b) **maggot-mass self-heating** — unrecognized, it makes development faster than ambient implies, *overestimating* the interval; (c) **species identification** — wrong species means wrong threshold/required-ADD constants, hence a wrong answer; (d) **developmental data uncertainty** — published rearing values vary and may not fit the local population. (Drugs in tissue (entomotoxicology) also qualifies.) **21.** A rare/localized assemblage is unlikely to be matched by coincidence, so a correspondence carries more weight — just as a rare blood type associates more strongly than a common one because fewer people (or places) could account for it. **22.** **Risk:** the "expected" date *anchors* the analysis — ambiguous specimens and stages get read toward the wanted answer (contextual/confirmation bias). **Safeguard:** keep domain-irrelevant information away from the analyst until the estimate is fixed, then compare; a *blind* estimate is worth more than one computed knowing the answer, even when they agree. **23.** No soot in the airways shows the victim was *dead before the fire* — i.e., dead and uncolonized while the fire burned and possibly suppressed early insect access. Fire that kills/repels colonizers and chars the openings can *delay* colonization, so insect age would understate the true time since death; the two findings sit consistently together, which is why entomology here is corroborating, not leading. **24.** **Honest:** "The pollen on the vehicle's floor mat is consistent with, and — given the assemblage's distinctiveness relative to the regional background — supports, the vehicle having been at or in contact with material from the cabin's environment." **Overstated:** "The pollen proves this vehicle, driven by the defendant, was parked in this exact clearing on the night of the fire."