Dr Martin Hall, Forensic Entomologist, talks to Rachel McLeod

Dr Martin Hallís 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 worldís 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 Hallís talk and spent the day with them both at the Natural History Museum in London.


Maggot treatment                                    healed

Maggots 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.

In the Sudan , you need to buy meat early in the morning before the flies get to it.  If you are late to get the meat, fliesí eggs have to be scraped off the meat before it can be eaten.


Thank you very much to both John and Martin for spending so much time with me. 


What insects do you keep?


I keep or collect a whole variety of insects, but mostly flies. Theyíre in the group called Diptera Ė Ďdipteraí means two wings, and all flies just have two wings. They actually have an additional pair of what used to be wings, theyíre called halteres now, but theyíre used for balancing.


If you were to keep only one insect, which would it be, and why?


Oh, thatís 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. Itís a fleshfly called Wohlfahrtís wound myasis fly (Wohlfahrtia magnifica) Ė just simply because Iíve studied that more than any other and I very much appreciate its behaviour. Itís a very handsome, white-with-black-spots fly. We donít, unfortunately, get it in England .


What was your favourite trip?


Probably 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.


How did you get involved in entomology?


When I was about ten I had just come back to England , and prior to that I was living in East Africa . Iím one of four boys, and as all boys do, we used to go outside and play a lot around the house. There was a lot of freedom in my childhood and so we were always bringing back things, all sorts of animals Ė snakes, you name it Ė and we had to sleep under a mosquito net. And whereas most people use the mosquito net to keep mosquitoes out, we used the mosquito net to keep insects in. So if we found any nice insects in the garden Ė big praying mantids, stick insects, even mammals, bats Ė we used to have them flying around inside the mosquito net with us. I loved insects right from a young age, and so I started to collect beetles as well. When I went to university, I thought that I might do marine biology. But when I was there I realised that it was insects that really excited me, so I changed and did a degree that included entomology, and then I did a PhD in entomology, and went on and was lucky enough to get a job in it, because there arenít that many jobs out there for entomologists.


What do you think is the best way to get people involved in entomology?


Get children involved as young as possible.  I conduct an annual ďbug huntĒ for all ages in some woodland and fields near to where I live in West Sussex .  Last year we caught insects in a field that had been cut by a tractor-drawn thing, and it was just plain grass, and then just next door to it there was a field that hadnít been mown, and we compared the diversity in the two fields. And you could see that where humans had come along and made whatís called a monoculture, all of one type of plant, there was hardly any diversity at all of insects, but in the field that was allowed to grow with all wild flowers, there were hundreds of different types. Perhaps theyíd walked across the fields before, and never thought to look underneath a leaf, or dig up a bit of soil and so forth, and so they were amazed at what you could catch.


Why is entomology important to you?


Itís important because itís an element of nature. If we didnít have insects weíd be really stuck. Just as a simple thing in my talk about maggots Ė if it wasnít for maggots our world would be full of much more slowly decomposing animals, because itís 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.


What is the most expensive piece of equipment you have bought for a trip, and why?


The most expensive piece of equipment I have bought is one Iím just about to buy, and itís called a thermal imaging camera. It can detect heat, and it will cost about £25,000. Itíll allow me to look at the behaviour of maggots in a way that you canít with any other system because I can photograph maggots when theyíre feeding in a big mass, and you can look at their temperature. Temperature is very important to maggot development, and itís 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, youíll find that theyíre actually quite hot, and that heat could speed up their development.


Are you scared of any arthropods?


I have to say no. I can honestly say Iím not scared of any arthropods. I do have respect for them, so Iím 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 Iím not scared of them, no.


What is the most embarrassing thing that has happened to you?


When 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 itís now in my collection, but it was a bit embarrassing at the time.


How do you become an entomologist in your sort of job?


There are fewer and fewer openings for them as a straight entomologist. Itís 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 thereís 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 donít seem to open, until finally they do open and you can get what you want.


What do you think would happen to insect populations if we suddenly disappeared off Earth?


Many insects would be happy to see the back of us, apart from some groups, theyíre called synanthropic species Ė 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 couldnít 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 youíd 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.


What have you contributed yourself to entomology?


Well, thatís 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 Ė thatís 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.


What are the biggest challenges facing entomology today?


Entomologistsí biggest threat is just being able to carry the banner that entomology is important. Itís 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 planetís diversity Ė all sorts of things


Whatís the most important question I could have asked you?


I think all the questions youíve 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 donít 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 donít need to know what they feed on, or what they do, theyíre just wonderful things. That was perhaps another answer I could give you for why insects are important: their beauty and their diversity.