Dr Martin Hall, Forensic Entomologist, talks to Rachel McLeod
Martin Hall’s interest in forensics has led him to maggots.
Maggots breathe through their back ends.
If they breathed through their mouths, when they were buried in dead
animals, they might suffocate. Rat-tailed
maggots breathe through their
tails because the live under water, looking for dead creatures to eat, so they
need to have this snorkel.
Maggots are the world’s recyclers. They eat all the dead bodies, much faster than they can decay by bacteria. So without maggots the world would be full of rotting animals. The life cycle of a maggot is the same as a beetle, except they turn into a fly as an adult instead of a beetle. These are the stages:
Dr John Church introduced a maggot treatment to the NHS. Now hundreds of different hospitals are using it. The maggots are applied in a mesh container like a tea bag. You put the bag into the wound and then the maggots hatch, eat all of the rotten flesh, and then it can heal, because the rotting flesh was preventing healing [photo]. Some species eat live flesh and some species eat rotting flesh. They are always one or the other. This is very lucky for the people who have maggot treatment! I met Dr Church at Dr Hall’s talk and spent the day with them both at the Natural History Museum in London.
are very useful in forensics as well. Dr
Martin Hall is a world-wide expert so he helps the police work out how long a
body has been dead for, by working out how many there are and how much of the
body is rotten and how much the maggots have eaten, how old they are and whether
there are any pupae. This depends on
the temperature of the body as well, and the species of maggot.
Thank you very much to both John and Martin for spending so much time with me.
insects do you keep?
keep or collect a whole variety of insects, but mostly flies. They’re in the
group called Diptera – ‘diptera’
means two wings, and all flies just have two wings. They actually have an
additional pair of what used to be wings, they’re called halteres now, but
they’re used for balancing.
you were to keep only one insect, which would it be, and why?
that’s a really hard question for an entomologist to answer, because they are
all worth keeping in their own way. I suppose I ought to choose a fly, really,
because I like them, so it would probably be a pest fly. It’s a fleshfly
called Wohlfahrt’s wound myasis fly (Wohlfahrtia
magnifica) – just simply because I’ve studied that more than any other
and I very much appreciate its behaviour. It’s a very handsome,
white-with-black-spots fly. We don’t, unfortunately, get it in
was your favourite trip?
working in Bolivia, in South America, and studying horseflies there, which in
that part of Bolivia were transmitting a disease which is very similar to
sleeping sickness in humans, it causes a similar disease but in cows. On those
trips I was able to live on a farm, and my bath was the river at the bottom of
the fields, and I could lie on my back and float down the river at night-time,
and look up at the sky and it was just full of stars, it was really beautiful,
and there would be fireflies as well, floating over the river, so it was a
really wonderful, unique experience.
did you get involved in entomology?
I was about ten I had just come back to
do you think is the best way to get people involved in entomology?
children involved as young as possible. I
conduct an annual “bug hunt” for all ages in some woodland and fields near
to where I live in
is entomology important to you?
important because it’s an element of nature. If we didn’t have insects
we’d be really stuck. Just as a simple thing in my talk about maggots – if
it wasn’t for maggots our world would be full of much more slowly decomposing
animals, because it’s maggots that cause the nutrient recycling, the quick
turnover of dead animals. Much more so than bacteria. They have a really huge
impact. And insects are important for such a huge number of things: pollination,
soil mixing, so many elements are welded together by the insects. They provide
food, for other creatures. And of course they have the downside, they can
transmit diseases and so forth, but there are many more pluses.
is the most expensive piece of equipment you have bought for a trip, and why?
most expensive piece of equipment I have bought is one I’m just about to buy,
and it’s called a thermal imaging camera. It can detect heat, and it will cost
about £25,000. It’ll allow me to look at the behaviour of maggots in a way
that you can’t with any other system because I can photograph maggots when
they’re feeding in a big mass, and you can look at their temperature.
Temperature is very important to maggot development, and it’s not been very
well studied so far what the impact of the maggot mass temperature itself is,
because maggots generate their own heat. If you put your hand into a mass of
maggots, you’ll find that they’re actually quite hot, and that heat could
speed up their development.
you scared of any arthropods?
have to say no. I can honestly say I’m not scared of any arthropods. I do have
respect for them, so I’m not going to go poking them if they could sting me or
bite me, for example some of those very large centipedes or, not so much the big
scorpions but the smaller ones you need to watch out for. So I have a healthy
respect but I’m not scared of them, no.
is the most embarrassing thing that has happened to you?
I was in Bolivia, we put our tents up underneath a straw roof, and there were
lots of wasps that were nesting there, and I can remember one night I was
brushing my teeth and I got a very painful jab in my bottom, and I had to pull
my trousers down and get rid of this wasp that had just stung me in my bottom.
But actually I managed to catch it, so I had the last laugh because it’s now
in my collection, but it was a bit embarrassing at the time.
do you become an entomologist in your sort of job?
are fewer and fewer openings for them as a straight entomologist. It’s
actually quite hard sometimes to be a specific kind of entomologist, like a
forensic entomologist, so I would recommend anyone just to try to study what
they love, and hopefully there will be opportunities that come up within that
field that they can then pursue. So there’s lots of potential out there, you
just need to be very tenacious and have a firm grip, to keep going forwards and
knock your head against the doors that don’t seem to open, until finally they
do open and you can get what you want.
do you think would happen to insect populations if we suddenly disappeared off
insects would be happy to see the back of us, apart from some groups, they’re
called synanthropic species – synanthropic means they have an association with
humans, so there are a number of species that co-exist with us, and there are
some species in Britain now, that can only live in Britain because we have nice
warm houses or nice warm grain storage silos that they can live in. So if humans
disappeared, the range of some insects would actually be reduced. Well, if
humans disappeared and they couldn’t just plant one type of plant, then lots
of wild plants would start coming in, and following them would be the insects
that feed on those plants, so you might not get any more insects, but you’d
get a greater diversity of insects around. And of course there are lots of
insects living in rainforests which would jump for joy if the humans
disappeared, because they would have a much better chance of success.
have you contributed yourself to entomology?
that’s a great question. Just a greater understanding of what goes on in this
disease called myiasis, where fly larvae feed on live animals, how the insects
find the host – that’s one area. The other area is perhaps in forensic
entomology, trying to improve the standards for sampling insects on human
bodies, and also to improve our ability to understand what they might be able to
tell us, improving our understanding of their development on bodies, and so
forth, and their distributions.
are the biggest challenges facing entomology today?
biggest threat is just being able to carry the banner that entomology is
important. It’s up to entomologists to keep their subject alive, and to
integrate it with other things, because entomology does have so much to
contribute to fighting disease, to improving our food production, to maintaining
the planet’s diversity – all sorts of things
the most important question I could have asked you?
think all the questions you’ve asked are great, actually, but the most
important one is probably: why is entomology important, or why are insects
important? And I gave you the standard answers about pollination, and their
importance in the ecosystem, but really, you don’t need to know anything about
that at all. You just need to look at a butterfly flying around, look at a
dragonfly, and you can appreciate them just for their beauty, really. You
don’t need to know what they feed on, or what they do, they’re just
wonderful things. That was perhaps another answer I could give you for why
insects are important: their beauty and their diversity.