Profile: ecologist Dr Henry Disney

Ulcerating lesions, botched burglaries and mysterious, blood-sucking flies – Dr Henry Disney’s passion for an order of winged insects has taken him from courtrooms to tropical rainforests, where his meticulous attention to detail has solved countless puzzles and generated a new understanding of an integral component of the natural world.

Disney graduated from the University as an ecologist in 1962. Fifty years later, as a Senior Research Associate at the University Museum of Zoology, his enduring fascination with the Diptera – a large order of two-winged insects including flies, midges and gnats – and scuttle flies in particular, continues to connect him with an incredible range of people and situations.

Back in the 1960s, Disney was a medical entomologist at the Dermal Leishmaniasis Research Unit in Belize, employed by the Ministry of Overseas Development.

“The people working in the rainforest were contracting a parasitic infection that formed ulcerating lesions on their skin,” he says. “It was my job to find out what insect was transmitting this. It was an unforgettable moment when I proved that the parasites in a sandfly I had dissected were in fact Leishmania mexicana, the cause of the problem. Within the first 100 years of medical entomology existing as a science I had the privilege of discovering a disease-transmitting vector.”

Disney went on to join the overseas staff of the Medical Research Council as the medical entomologist at the Helminthiasis Research Unit in Cameroon, where he investigated black flies in relation to river blindness, before returning to the UK to run the Malham Tarn Field Centre and natural nature reserve in North Yorkshire.

“In Yorkshire they had done a big insect survey in the 1950s, but they hadn’t dealt with scuttle flies because the taxonomy was in such a mess. The textbooks said they were all muck-breeders, but I didn’t agree. I found one scuttle fly species parasitising the larvae of a lesser fungus gnat, and another preying on slug eggs. So I set out to put together a complete list of species for the nature reserve, this time including the scuttle flies.”

That said, many scuttle flies do breed in muck – or decaying organic material to be more precise – and this includes human corpses. It was their predilection for dead bodies that led to one species being nicknamed the coffin fly. Since his return to the University’s Department of Zoology, Dr Disney’s expertise has led him to be involved in high-profile murder inquiries in which scuttle flies have provided key evidence leading to a conviction.

“There was a case in Sussex in 1999 in which a man broke into an elderly lady’s house. He killed her and left her on the floor before working through the house over the next few weeks, even forging her signature on cheques to pay the bills and keep up the pretence that she was still alive.”

When a species of scuttle fly was found on the body in the ensuing forensic investigation, Disney was called in. “I worked out that the fly eggs had been laid in July, which conflicted with the written evidence of the date of death,” he says.

“This proved that the offender had been lying. In the end the whole case hinged on the scuttle flies.”

Dr Disney has also been asked to identify and comment on specimens submitted for forensic examination by trading standards officers, commercial companies under threat of litigation, and animal welfare officers.

“I’ve abolished a lot of species and contradicted a lot of facts in textbooks about scuttle flies over the years,” he says. “In the 1990s I got funding to pull together everything that was known on scuttle flies, and I published a key to world genera, and a review of the world literature. I started finding new species in my own garden – I became an obsessive.”

With the subfamily Termitoxeniinae, whose highly aberrant females live in the fungus gardens of termites: “What have been described as different species of scuttle fly have, in many cases, turned out to be the same species at different stages of their development,” says Disney.

“In one case, I took a sample of these females – presumed to be various different species – from a termite nest in Java. I mounted the flies on microscope slides and measured the lengths of their hind femora. When I plotted a graph of femora length against the lengths of the developing eggs the flies contained, there was a perfect correlation. These different-sized flies were actually the same species, just growing. To grow, which is not usual in adult flies, it was hypothesised that by imbibing juvenile hormones from the blood of the termites they were preventing cessation of growth as adult flies.”

In 1995, the Leverhulme Trust funded Disney to travel to the Far East to try to unravel the uncertain and much debated taxonomy of Termitoxeniinae. “I revised the taxonomy of the Afrotropical and the Oriental species. The latter enabled my Japanese collaborator Dr Munetoshi Maruyama to identify species found living in the extreme south of Japan, and to recognise a whole new genus. This led to a publication in Entomological Science in 2011 that aroused exceptional interest, and has just won an award from the Entomological Society of Japan.”

Dr Disney’s work has led to many important publications, including the popular Naturalists’ Handbooks series, which he started and co-edited with colleague Dr Sarah Corbet, helping thousands to undertake field studies and make accurate identifications across a whole range of taxonomic groups. He has also published the only book ever devoted to scuttle flies, plus a staggering 500 papers on this family of insects.

“Ninety per cent of the flies I work on are sent to me from other people,” said Disney. “When people heard I was working on scuttle flies, they started asking me to look at specimens they had.” Through many decades of observations at the microscope, Disney has become intimately familiar with the critical features of the scuttle fly, and his expert eye now enables him to identify them, and determine whether they are entirely new species.

“I greatly enjoy sorting out the taxonomy to help people with the publication of novel natural history data they have obtained,” he says. “For example, a new species found in Trinidad whose larvae prey on the eggs of a frog, and another whose larvae feeds on the pollen stores of a solitary bee in Australia. At the moment I’m looking at a collection from ancient forests in England. I’ve already got three species new to science, and this is from Britain, which has the best documented fauna in the world.” 

Dr Disney’s work has enabled him to amass the greatest collection of slide-mounted scuttle flies in the world at the University Museum of Zoology. A staggering 638 of his 1,296 named species are ‘Type’ specimens, which are of the highest scientific importance, acting as the universal references for classifying and naming species.

“I’m really an ecologist who found that every question comes back to taxonomy, because you keep finding things that aren’t in the literature,” he says. “When I was a graduate student studying ecology at Cambridge in 1962, I shared the common view that taxonomy was something the Victorians did. But in fact we now realise that about 80 per cent of the species on planet Earth are actually unknown to science, and fundamental taxonomic work is vital. The habits of most species remain unknown, so there is still a great deal for naturalists to explore.”