UF Animal Forensics Conference 2024: Forensic Entomology (Bugs!!!) with Jason Byrd

DrG: 00:00:04

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.