We are in person at the 2024 Animal Forensic Conference in Gainesville, Florida! Dr. G will be interviewing several of the speakers to give our audience a bit of the knowledge gained through the presentations. We will be releasing each interview individually to allow our listeners to find topics of interest.

Dr. Jason Byrd, Board Certified Forensic Entomologist, discusses the use and importance of insect collection at crime scenes and from deceased animals, how to submit them, and the information that can be obtained from this forensic tool.

We would also like to invite our listeners involved in animal cruelty investigations to visit and join the International Society for Animal Forensic Sciences https://isafs.org/

Mentioned in this episode:

Keep it Humane Podcast Network

The Animal Welfare Junction is part of the Keep It Humane Podcast Network. Visit keepithumane.com/podcastnetwork to find us and our amazing animal welfare podcast partners.

Next guest is Dr.

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Jason Byrd.

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Thank you very much and

welcome to The Junction.

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Jason Byrd: Thanks for having me.

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DrG: So, what is your background and how

does it relate to the field of forensics?

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Jason Byrd: Well, so I'm a forensic

entomologist, and, uh, we specialize

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in using insects to help us determine,

uh, most commonly it's the post

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mortem interval, or portions of

the post mortem interval, so how

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long an animal has been deceased.

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But entomology can be useful in

determining, uh, a geographic origin,

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you know, where the, uh, original,

uh, colonization may have been.

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Uh, may have occurred if the

animal has been transported.

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Uh, we can use it for, uh, toxicology.

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See if there's any drugs

or toxins on board.

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Cause you can use maggots gram for gram

as you would the, the animal tissue.

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And, um, a genetic analysis.

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Because at some point in time these

insects are going to leave what

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they were feeding on and distribute

themselves out in the environment.

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Um, and they'll spend 60

percent of their life cycle at

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least out in the environment.

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Um, so if a crime scene investigator

recovers some of these insects and they're

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not, are associated with the body, we have

to prove that they did come from the body.

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So we can do a genetic analysis to,

uh, A, determine their species, so we

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know what we're dealing with, and then

B, determining what they were feeding

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upon to, to match it to the, you know,

the animal in question or the, the

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human remains in question at a crime

scene to prove that indeed it came from

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that body and then this estimation is

then going to give us a post mortem

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interval that relates to that body.

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DrG: So I know that the main question that

people ask you is basically how long dead?

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Now, is that what the insects

are actually telling you?

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Jason Byrd: So there's a

bit of a debate on that one.

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Um, so entomologists, uh, disagree

a little bit, but in my work,

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I try to use, uh, when I send a

report to an investigator, I try

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to target the time of colonization.

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That's when the flies were depositing

eggs or maggot on that human or animal.

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Um, and I use that because that is

the point that biological clock starts

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with the insect growth on the body.

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And then we can put them in

environmental chambers, different

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temperatures, we can rear them under

different light cycles, so we can

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put a lot of statistics to that part.

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So that is the time of colonization.

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And I can say that, you know, the

individual, be it human or animal,

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was it dead, you know, on or before

colonization, because if we're dealing

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with mice, those are different species.

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So we can, you know, rule

that out in most cases.

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But that may not be the time of death,

because the time of death could have

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preceded the time of colonization.

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And it makes sense, because somebody

dies, an animal dies, it takes

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a while for flies to, you know,

be able to show up and find it.

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The problem with that is, is, That's kind

of a different set of research, right?

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Uh, fly arrival rates, how long

does it take them to get there?

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How are they impacted by light and

dark cycles as far as sunrise and

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sunset and different weather patterns?

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And that for many species, we

just don't have that type of data.

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And even for the species that we

do have, that type of data is from

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really limited research areas.

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So to avoid all of this, um, you know,

one off situation that's hard to repeat

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and then really becomes more, um, a

professional opinion than anything else.

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Uh, I don't, I don't put any of

the pre colonization interval

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information in my reports.

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I just do the post colonization or

time of colonization try to target.

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And then, you know, they

want to know how long dead.

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So it's not going to maybe give them

how long dead, but it gives them

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a huge portion of how long dead.

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And then sometimes that's enough,

you know, it can make or break

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alibis, puts people in particular

places at particular locations.

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But I feel more confident with

being able to stay with what

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we can put some statistics to.

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DrG: I love watching crime,

crime shows, but I look at them

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for the entertainment value.

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Right.

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And looking at it, it's kind of funny

about the, you know, how quickly and how

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decisive they are in, in their findings.

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But that's not really

the, the case, right?

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Like in the, in these shows,

somebody will look at.

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Some maggot in the field and

say, this is exactly this bug.

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And this body has been dead for X amount.

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And then when I took the, the forensics

masters from UFL and during entomology,

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I realized that the, the range

that's given, it's not as precise.

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So what are the factors that go into

that and how long can a range be?

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Jason Byrd: It depends.

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I mean, So the range, um, one

is what species is it and how

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much information do we have.

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There are some species that's never

been reared in the laboratory.

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So if you happen to have that scene,

your, your range is pretty broad

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because we don't know what it's doing.

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Um, so that is one.

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And even if you do research on

them, there's biological variation.

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I mean, just think of a litter

of puppies or kittens, you know,

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some will outgrow the other.

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Same thing with a, a, an aggregation of

maggots that may be deposited from the

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same egg clutch from the same female.

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Some will grow a little

bit larger than others.

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So there's that biological variation.

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And then, since they are so heavily

influenced with temperature, the

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big variation in these estimates

that come in is like how, how

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accurate do we feel we are with the

thermal history of these insects?

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And then how close was

the weather station?

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Is it certified data or not?

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And, you know, are the conditions

at the scene fairly consistent

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with wherever we're getting the

information from the weather station.

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So when you put biological

variation, variations in weather,

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um, the species itself, which we

may have good data on, may not.

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I mean, maybe some of the

data was done in the fifties.

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So, you know, how much, how much genetic

drift has happened since that time

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that may, you know, They may be growing

faster or slower now, current populations

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than what was happening in the 50s.

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So when you put that all together,

your variation can be pretty broad.

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So to help with that, we try to

constantly do research on new species.

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Um, we try to maybe put data loggers

at the scene, to record many more

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temperature data points and what

your crime scene tech is going to be.

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And we'll try to get, you know,

most of our windows of opportunity

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Um, let's say, you know, maybe the

body's been dead for two weeks.

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Um, and we're trying to plot

back to a time of colonization.

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So we can usually get that time of

colonization down to usually plus

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or minus 36 or 48 hours or so.

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So not that much, um, variation

at that point in time.

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But when you get months out, you know,

maybe your variation is a week, two weeks.

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So it's also depending on how long your

ultimate postmortem interval is as well.

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So can vary quite a bit in some cases.

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DrG: What's the, what's the kind

of information that you need from

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an investigator to help you do your

job as far as the things that they

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need to collect on the scene, both

insects and environmental factors?

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Jason Byrd: Yeah, well, we need

temperatures, lots of temperatures.

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The air temperature, the body

temperature, the ground temperature,

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um, that's if it's outside.

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And of course, if it's inside, you

know, all the interior temperatures,

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whether utilities were on or

off, what was the thermostat set,

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you know, ceiling fans on, off.

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Okay.

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Doors and windows open, closed.

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So just the environmental temperatures is,

is, is one, you know, um, large area that

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we would, we really need them to document.

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Um, and probably that's the most valuable.

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The other is just sample size.

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We often have a problem with the,

um, crime scene investigators or

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animal control officers, you know,

whoever may be making the collections,

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we're just not quite getting enough.

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You know, we need 50 or 60 to

get, get a good statistical size.

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Uh, maybe they give us five or six.

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Um, and you can look at the pictures

and see that there are probably

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some species that's just not

represented in their collections.

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Um, so that's another one.

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So getting a representative sample,

um, and getting enough of what they

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do see is usually the big challenge.

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DrG: I know I, uh, many, many years

ago, I sent you a case of a dog that

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had died in a basement and then it was

moved outside and you were able to give

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us like we just wanted to know if the

body was dead for more than a week and

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you were able to give us a minimum time

of colonization of about three weeks.

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One of the things that did not happen,

though, is that the primary crime

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scene had a lot of larval casings.

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And the investigator did a great

job at taking photographs of it, but

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they did not collect any of them.

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So, what is the importance as

far as collecting things on

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the scene versus waiting until

the necropsy to collect them?

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Jason Byrd: Well, it's most important

to collect at the scene because

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these insects, once they're through

with their feeding period, are

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going to wander away from the body.

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They don't stay associated with it.

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So, always the older ones.

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Which could be the biggest question

the investigator has, you know, what's

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my maximum post mortem interval?

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Those older ones are going to

distribute themselves around the scene.

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So if you just come in and collect off

the body, pick up the body and leave,

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you know, you're missing probably the

most important part of that picture.

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Then the other issue is sometimes

they don't make a collection.

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Um, scene is done, they then realize,

ooh, well we should have collected

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entomology, that could help us, and

then they ask us to look for photos.

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Sometimes that's possible because some,

uh, species are distinct enough that you

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can identify them in the photographs.

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But the big problem is, for the vast

majority of these insect species, you have

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to put them under, you know, a microscope

and get that level of magnification

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before you can really tell what they are.

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Um, and so in a photo from a regular, you

know, digital SLR, they all look the same.

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And the problem with that is,

they look the same, but some

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of them can grow very quickly.

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Some species and some

species grow very slowly.

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So it's not like you can even just

group them and say well I know, you

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know, just the, the, the average

group of, um, you know, maybe the

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genus that this fly comes from.

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It doesn't help you because within

that genus you can have some

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very fast developing flies and

some very slow developing flies.

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So you really need the specimens

themselves, um, sent to you

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to back up the photographs.

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DrG: What's going to be the best way

for investigators to collect these

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samples to send them to you so that

you can do a good job in identification

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and in determination of the time?

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Jason Byrd: Well, I mean, the

best thing is, you know, uh, there

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are plenty of, um, uh, equipment

checklists that are out there.

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So you configure yourself an entomology

collection kit that has all the tools

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that you need before you go out and do it.

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Um, but we basically need, um, a live

collection and a preserved collection.

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That live collection helps us with the

identifications because the adults are

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usually distinct where the larvae are not.

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Um, so we need the collections

themselves, live and preserved.

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We need the weather data and photographs.

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Um, and a collection of the adults

that are just flying around the scene.

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Um, some entomologists say there's

really no need to worry about that

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because we don't use them for post

mortem interval estimations anyway.

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Um, and that's true to an extent.

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You don't age the adults, but

the adults can help you determine

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what larvae are present.

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And the adults also can tell

you what habitat, you know,

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you would expect to be in.

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Which can be important because if I

see, um, you know, adult flies, they're

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sun loving flies, they like really hot

weather, and the crime scene is indoors

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or in a shed, then I can tell you that

at some point in time that animal was

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outside, it was colonized, and somebody

brought it in for concealment purposes

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or something like that, or vice versa.

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You're out in the middle of an open

field on a bright, sunny day, and

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we have a bunch of shade loving

insects that like relatively cool

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weather, so you know that at some

point in time that animal was inside

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and it had been dumped, essentially.

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So just having a good scene collection

of the representative samples that

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are there can Also help us confirm

that that scene is where that animal,

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um, you know, um, decomposed or,

or died and wasn't transported from

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somewhere else and just dumped.

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DrG: So the other case that I had

submitted to you was a lot different

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because there were a large number

of deceased animals and there

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was a lot of insect activity.

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However, there was no information

collected on temperature, location.

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and the estimated time of death

was six months to over two years.

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So is there any information

that you can get from that or

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is that just kind of useless?

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Jason Byrd: It depends

on the species, really.

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Um, so I wouldn't say it's useless,

um, with some species because

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And the other species will tend to

recolonize year after year after year.

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So it really just depends on the species.

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But if you've got one species,

we'll kind of go through their

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entire life cycle in a year.

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And then you've got new documentation

that they've at least completed

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that life cycle, then you

know it's a minimum of a year.

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If it's a species that are recycled

year after year after year, you

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know, you've got a lot of dead flies

on the windowsill and on the floor.

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You don't know what generation you're in.

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You know, it could be three years.

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So it really just depends on the species

that you're dealing with as to what they

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tend to do and whether they recolonize the

remains and start their cycle over again.

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Generally, they don't.

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That's the reason entomology works.

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They will deposit their eggs, they

go through their life cycle, and when

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that species hatches out, it goes away.

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It's not interested in

those remains anymore.

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So entomology is just like

input and output for the

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vast majority of the species.

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DrG: So what resources are out

there for investigators and forensic

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veterinarians and such to learn about

how to collect the specimens, how to

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submit them, and that kind of stuff?

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Jason Byrd: Yeah, there are several

books on forensic entomology, some field

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manuals, um, most of the board certified

entomologists have their own website.

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Um, but yeah, I mean, it's pretty easy

to be able to find a, either from books

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or from the internet, a checklist of

the equipment that you need, uh, the

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various forms that you need to be able to

properly document all the environmental

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data, uh, chain of custody forms, of

course, for your entomology collections.

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And then, you know, the, uh, American

Board of Forensic Entomology, uh,

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has a list of all the boarded, um,

forensic entomologists on their

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websites and their geographic locations.

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So you can find the nearest

boarded entomologist to you.

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But you don't really need a

boarded forensic entomologist

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to get help at the scene.

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I mean, you know, there's

only, uh, there's less than 30.

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Not very likely you're

actually going to get them.

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Um, but you need an entomologist.

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But entomologists are everywhere.

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They're at our schools, museums.

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You know, colleges and universities,

the Agricultural Extension Service.

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So you just need to make a relationship

with an entomologist in your

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area to be able to help you out.

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And then they may have, you know, the

specialized collection tools, forceps

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and nets and all that to be able to

loan you if you're in their area.

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So it's not hard to get

entomology help these days.

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DrG: I think it's a very valuable

tool, right, especially for forensics.

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, I really want to thank you for taking the

time and thank you for what you're doing.

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Jason Byrd: Yeah, thanks for being here.