Dame Miriam Rothschild

Expert on fleas and energetic campaigner for nature conservation

Miriam Rothschild was a distinguished zoologist and a dedicated champion of animals and plants, both wild and domestic. Although she was among the most celebrated entomologists of the 20th century, she considered herself to be more of an amateur naturalist than a scientist. More important than formal qualifications was her naturally agile and enquiring mind, allied to the tendency she ascribed to her family as a whole: to become deeply, almost obsessively, involved in everything that interested them.

Miriam Louisa Rothschild, zoologist, writer, gardener, farmer and campaigner: born Polebrook, Northamptonshire 5 August 1908; Editor, Novitates Zoologicae 1938-41; CBE 1982, DBE 2000; FRS 1985; married 1943 George Lane (one son, three daughters, and one son and one daughter deceased; marriage dissolved 1957); died Ashton Wold, Northamptonshire 20 January 2005.

Miriam Rothschild was a distinguished zoologist and a dedicated champion of animals and plants, both wild and domestic. Although she was among the most celebrated entomologists of the 20th century, she considered herself to be more of an amateur naturalist than a scientist. More important than formal qualifications was her naturally agile and enquiring mind, allied to the tendency she ascribed to her family as a whole: to become deeply, almost obsessively, involved in everything that interested them.

Undoubtedly her guiding spirit was her father, Charles Rothschild, despite his early death in 1923, by his own hand when she was 15. It was the daughter's duty to his legacy - cataloguing the world's largest private collection of fleas - that led to an outpouring of experimental work on the life of insects and their relationships with plants, and with each other. An unorthodox and eclectic education gave her another rare quality - perhaps unlike most other great scientists, Rothschild always had her feet on the ground. Her life's achievement was almost as fruitful in influence as in original research.

Believing that a formal education was a waste of time, her father encouraged Miriam to pursue anything she found interesting. At 17 she enrolled for university courses in her twin passions of zoology and English literature, but, despite showing an unusual talent for both, never offered herself for the degree examinations. As she recalled, "You always wanted to hear somebody talk on Ruskin when it was time to dissect a sea urchin."

In need of experience in her chosen field of parasitology, she took up a post with the Marine Biological Association at Plymouth, studying snails and their parasites. Though the work was often tedious, it taught her basic techniques in dissection and slide preparation. After the death in 1937 of her uncle Walter, the second Lord Rothschild, creator of a private zoological museum at Tring Park in Hertfordshire, Miriam also edited the Tring museum journal, Novitates Zoologicae.

During the Second World War, Miriam Rothschild joined the team of biologists, philosophers and mathematicians at Bletchley Park under Alan Turing, working on the now famous secret project to decode German communications sent by the Enigma machine. Using "intensive mathematical and logical analysis" to crack the code, Rothschild later claimed that the biologists more than held their own against the maths boffins. During that time, she met her future husband, George Lane, a Hungarian exile, whom she married in 1943; they went on to have two sons and four daughters.

At other times she worked for the Ministry of Agriculture, producing a new form of chicken feed made from seaweeds, and establishing, through repeated dissections, that wood pigeons could carry bovine tuberculosis and so threaten beef production. She also found time to train as an air-raid warden, and qualify as a milkmaid.

After the war, she continued to work on the biology of parasites, particularly fleas. She catalogued her father's vast collection of slide-mounted specimens in An Illustrated Catalogue of the Rothschild Collection of Fleas, published by the Natural History Museum in six volumes between 1953 and 1983. This, her magnum opus, was done in collaboration with Harry Hopkins, a retired civil servant. It required much original, descriptive work on insect tissues or, as Rothschild herself put it, "staring at the backsides of fleas". The writing and checking of over 7,000 drawings was done mainly at night after the children had gone to bed. Perhaps fortunately, she was a lifelong sufferer of insomnia.

Among many published scientific papers on the loathsome but intriguing insects that so captivated Miriam Rothschild and her father, two major discoveries stand out. One was the discovery of a rubbery fluid in the flea's hip-joint which enabled it to make its prodigious jumps - equal in speed to a moon rocket and capable of being repeated hundreds of times without (so to speak) drawing breath.

The other demonstrated how the rabbit flea could control its fertility to coincide with that of its host, and so accurately that baby fleas were able to drop straight on to new-born rabbits. During the myxomatosis outbreak of 1954, Rothschild served on the Government's advisory committee under Lord Carrington, which correctly identified the vector as the rabbit flea, and not, as had been thought, a mosquito.

In 1952, she published her classic study of bird parasites, Fleas, Flukes & Cuckoos, in collaboration with Theresa Clay. The book was a surprise success, thanks largely to the author's lively, witty style in which she addressed such matters as what birds would talk about if they could speak, and the lives of extraordinary beasts like the worm that feeds on the tears of a hippopotamus, or the fluke that wanders from the liver of a snail to the body cavity of a shrimp and "ends up living happily ever after under the tongue of a frog".

There was, as one critic exclaimed, a wonderful nightmare in every paragraph. The opening chapters of the book were written from memory, without any textbooks, while the pregnant author was marooned in Calais during a Channel storm, living on a diet of boiled potatoes. A later work, Atlas of Insect Tissue (1985), had for a jacket illustration a close-up illustration of the vagina of a flea, a choice which, Rothschild claimed, rendered it unique.

Miriam Rothschild's second love was butterflies. In one Who's Who entry she described her hobby as "watching butterflies". However, her idea of close observation involved original research into the strange chemical world of flying insects and the colour codes hidden on their beautiful wings. The greenhouses at her estate at Ashton Wold, near Peterborough, were normally full of Cabbage Whites, Monarchs and Heliconid butterflies from South America. As with her flea work, most of her research was done at home, in collaboration with biochemists and other specialists at the universities.

A key finding was the ability of butterflies to sequester and store toxic chemicals from their larval food-plant and use them as part of their chemical arsenal. For example, the Cabbage White stores mustard oils from cabbages, and transfers them to its eggs and caterpillars. The butterfly goes out of its way to be easily visible in all the stages of its life as a sign to birds that it is unpalatable. But the strategy seems to falter with mammals, as Rothschild discovered after watching a tame fox catching and eating the Cabbage Whites with apparent enjoyment.

In 1991, she published Butterfly Cooing Like a Dove, which she described as a "crazy book about aire and angels", about "doves, the symbol of the spirit, and butterflies, the symbol of the soul".

When she was in her late sixties, Rothschild abandoned her brass microscope to concentrate on animal husbandry and nature conservation. "I woke up suddenly one morning," she explained,

and looked at the fields. Not a flower in sight. Modern agriculture had bulldozed, weed-killed and drained all the flowers out of the fields that I'd known as a child. We were living on a snooker table.

Rothschild's solution was to cultivate wild flowers from disused local fields for sowing back, especially on the banks of bypasses and other prominent public places. In 1995, wild-flower seeds from Ashton Wold were sown in over a thousand school grounds. Thanks to her energetic campaigning at the Chelsea Flower Show and elsewhere, the recreation of flower-rich habitats became positively fashionable. Among her "disciples" was the Prince of Wales, who used Rothschild's principles when planning his garden at Highgrove.

Ashton Wold, the mock-Elizabethan manor house built by her father, and where Miriam Rothschild lived most of her life, under her direction became the centre of a de facto nature reserve. An area requisitioned as an airbase during the war became "an ideal opportunity to put my pet theories into practice". Now called "The Roughs", it was left to develop naturally, as were some of the woods on the estate. Fields cultivated during the war have been re-established as hayfields where no fertiliser or herbicides are allowed. There was even, for a short while, a unique "dragonfly museum" established in a disused mill, with views over a section of the River Nene normally buzzing with insects.

Rothschild was also a vigorous campaigner on a host of related issues, from the iniquity of road works to the misuse of animals, whether in laboratories, factory farms or slaughterhouses. She created a Schizophrenia Research Fund after the death of her sister Elizabeth, who suffered from the illness. of "All my life," she said, "I have tilted against hopeless windmills." Many of her causes seem less hopeless now.

Conversation with Miriam Rothschild was invariably stimulating, if sometimes chaotic. One jumped like her favourite fleas from one thing to the next, from whether dogs made plans or quails had a memory, to experiences with ghosts and the pleasures of watching snooker on television. Though confined to a wheelchair in her last years and increasingly frail, she was always mentally agile, and always a perfect host.

She possessed in good measure a gift she attributed to her father: "He always made other people feel clever." In the mind's eye she is always there in the big book-lined room overlooking the hayfield, with its grand piano and open fireplace, wearing her trademark shawl, reading glasses on a cord round her neck, perhaps even the white wellies she is supposed to have worn at Buckingham Palace, in disapproval of boots made of leather.

Rothschild was appointed CBE in 1982 for services to taxonomy. In 1985, the same year she gave the Romanes Lecture at Oxford, entitled "Animals and Man", she was elected a Fellow of the Royal Society (following her brother Victor, the third Lord Rothschild, making them the only brother and sister to be so honoured). She received many awards and honorary degrees in Britain, the United States and Germany. In 2001, the charity Butterfly Conservation presented her with a Lifetime Achievement Award "for love of Lepidoptera and dedication to nature conservation and research on British butterflies". She became a Dame in the New Year's Honours of 2000.

Miriam Rothschild was once asked to name her personal "Seven Wonders of the World" for a television programme. Her choice matches the characteristic mixture of eccentricity, charm, international outlook and eclectic learning one associated with Rothschild. They were: the Monarch butterfly, the Tiger-moth earmite, the Jungfrau, the life-cycle of the parasitic worm Halipegus, the jump of the flea, Jerusalem glimpsed in a sandstorm and carotenoid pigments.

Peter Marren