Collection, Preservation and Rearing of Insect Samples

February 27, 2008

The Entomologist at the Crime Scene

• Should be at scene with initial investigation team

• Should have access to autopsy

• Request scene photos

• Proper collection kit

Collection kit

• Net

• Vials and Kill Jars

• Forceps and small paint brushes

• Live specimen containers, foil, vermiculite, and food

• Labels (adhesive and non-adhesive)

• #2 graphite pencil

• Hand trowel or garden spade

• Thermometers

• Camera

• Ruler

• Preservation and collection chemicals (Ethyl alcoholethyl acetate)

• Small backpacking stove or other heat source andBeaker, Water

• Paper towels

• Disposable gloves

• Sifting screens

• Death scene form

Scene Observations and Weather Data

• Observations of the scene (use death scene form)

• General habitat/location of body

• Sun, shade, vegetation, proximity to doors/windows (esp. if open)

• Insects and stages, locations

• Vertebral scavenging

• Predation of insects

• Possible insect artifacts on body

Collection of meteorological data at the scene

• Ambient air temperature (approx. chest height)

• Maggot mass temperature

• Ground surface temperature

• Between body and ground

• Soil under body

• Max/min daily temperatures at scene for 3-5 days

Weather data

• Approx. 2 weeks before--3-5 days after discovery

• Nearest weather station

• Max and min daily temperatures

• Rainfall

Insect collection at the scene: From the Body

• Adults first

• Pinned/in alcohol

• Label correctly--inside and out

• Use pencil only

• Larval Collection

• Largest most important

• 50-60 preserved, others live for rearing

• Representative sample of everything

Geographical LocationDate/hour of collection

Case #Location on BodyName of Collector

Insect collection at the scene: Around the body

• Exam area around in body

• Concentric circles

• Soil samples

• Beneath bodyesp. near maggot mass

• Litter Samples

Insect collection at Autopsy

• May find different stages

• Clothing, body bag, other areas of bodies

• Take into account cooling

Identification and Rearing

• Identify largest insects first

• Maggots may be hard to identify

• Rear out live insects to identify adults

• Estimate degree days

Larvae Identification

• Larvae look similar

• Easiest to identify 3rd instar

• Spiracles, mouth hooks

• Larger, easier to see

• 1st and 2nd instar: 2 spiracle slits

• 3rd instar: 3 spiracle slits

Larvae Identification

Mouth hooks

Spiracles

Move by extension/contraction of body

Change slightlyeach instar

PS: pharyngeal sclerite

DC: dorsal lobes of PC

VC: ventral cornua of PC

HS: hypostomal sclerite

MS: mandibular sclerite

DS: dental scleriteMH: mouth hook

DO: external dorsal sensory organs

Muscid

Phormia Lucillia

Peritreme Outer slit

Middle slit

Inner slit

Button

Identification and Rearing

• Identify largest insects first

• Maggots may be hard to identify

• Rear out live insects to identify adults

• Estimate degree days

Any Questions?