1. Insect Biology Entomology 2

2. Phylum Arthropoda Largest phylum on Earth –75% of all living species Class Arachnida (spiders, ticks, scorpions…) Class Crustacea (shrimp, crabs, crayfish…) Class Insecta Class Diplopoda (millipedes) Class Chilopoda (centipedes)

3. Class Insecta Largest class of animals on Earth –~800,000 species Over 200 million per person History includes over 250,000,000 years of Earth history Many species still undiscovered Populate EVERY habitat on Earth Approximately 90,000 to 125,000 species in North America alone

4. Class Insecta 3 body parts –Head –Thorax –Abdomen 6 jointed legs –3 pairs on thorax Exoskeleton 2 antennae Compound eyes

5. Class Insecta Metamorphosis –Describes the way by which insects change, grow, develop from egg to adult –All insects undergo some type of metamorphosis due to exoskeleton –Referred to as “moults” –Many adults do not feed…adult phase for mating only Incomplete (12%) –Gradual change over time –Young looks similar to adult Complete (88%) –4 distinct stages

6. Incomplete Metamorphosis Egg Nymph –Small adult –Lacks wings –Several stages Adult

7. Complete Metamorphosis Egg Larva –Worm like –Maggot, Caterpillar… –Molt several times Pupa –Cocoon Adult

8. Order Diptera “Two wings” Includes flies of all varieties, mosquitoes, gnats Many feed on rotting flesh or other decaying matter –Highly in tuned sense of smell is common

9. Order Diptera Forewings are membranous –Used for flying Hindwings are for balancing –“Halteres” – knob like Metamorphosis-Complete Mouthparts-sucking (most) –All forensically valuable species

10. Blow/Bottle Flies Flies usually infest first because larvae (maggots) can survive in the liquid medium of the corpse.

11. Blow Flies Kingdom –Animalia Phylum –Arthropoda Class –Insecta Order –Diptera Family –Calliphoridae Genus –Cynomyopsis Species –cadaverina

12. Medicinal Uses of Maggots Well documented cases in medicine for centuries Maggots will selectively eat dead tissue before living tissue “Maggot therapy” is an accepted method for fighting infections –Now seeing a resurgence due to MRSA*, etc. WARNING – GRAPHIC IMAGES *Methicillin-resistant Staphylococcus aureus

13. Maggots in leg amputation

14. Maggots in Wound

15. Maggots in small cavity wound

16. Order Coleoptera “Sheathed wing” Largest group of insects –25% of ALL living species Includes the beetles and weevils 350,000 known species Forewings are hard; cover hindwings Hindwings are membranous –Used for flight –Wings meet in straight line down the middle of the back Metamorphosis-Complete Mouth parts-Chewing Usually eat the fly larvae rather than the corpse

18. Carrion Beetles Kingdom –Animal Phylum –Arthropoda Class –Insecta Order –Coleoptera Family –Silphidae Genus –Necrophila Species –americana

19. Determining Time of Death Known as Post-Mortem Interval (PMI) Use insect stage (instar) to determine the time since death –Maggots have 3 instars (or molts) before pupa Must consider: –Temperature –Time of day –Exposure of corpse (air, soil, water)

20. PMI Determination ID species –Different species usually arrive in specific orders based upon senses Document larval length Measure maggot size Determine instar –Can be determined by examining body features Calculate PMI

21. Species Identification Look at structural differences –Body Shape –Color –Texture –Mouth hooks (at tapered end) –Spiracles (at blunt end)

22. Determine Instar Look at the Posterior End of maggot Breathing “spiracles” are located here Count the number of spiracle slits to determine the instar

23. Spiracle Slits Spiracles used for breathing by the blow fly larvae.

24. Mouth Parts Mouth hooks used by blow fly larvae to attach themselves to a food source. As a reminder, the larvae have no legs.

25. 1 st Instar 0-36 hours after eggs are laid 2 mm to 5 mm 0 to 1 spiracle slits

26. 2 nd instar 36-72 hours 5 mm to 10 mm 2 spiracle slits

27. 3 rd Instar 72 hour + 15 mm to 20 mm 3 spiracle slits

28. Pupa Pupa cases usually found within a few feet of food source Cases can last for decades

29. Establishing Time of Death

30. Stages of Decomposition Experiment WARNING – GRAPHIC IMAGES

31. Living Pig

32. 0 to 3 days Fly Eggs in EAR

33. 4 to 10 days

34. 10 to 20 days

35. 20 to 50 days

36. 50 to 365 days

37. Facts! In warm weather, maggots can digest 60% of a human body in less than a week!