Harold Maxwell-Lefroy (20 January 1877 – 14 October 1925) was an English entomologist. He was a Professor of Entomology at Imperial College London who was posted as the first Imperial Entomologist to India. He worked on applied entomology and initiated experiments on the use of chemicals to control insects, founding the Rentokil company.
Maxwell-Lefory was born in the village of Crondall, and attended Marlborough College and King's College, Cambridge, matriculating in 1895 and receiving a BA in the natural science tripos with first class in 1898 followed by a masters degree in 1902.
He served as assistant master of Seaford College, and later worked as an entomologist in Barbados from 1899. In 1903, Lefroy was appointed entomologist to the Government of India (succeeding Lionel de Nicéville, who was the first entomologist, appointed in 1901). Then in 1905 he was involved in the creation of the Imperial Agricultural Research Institute in Pusa, in the Indian state of Bihar, and he was appointed the first Imperial Entomologist.
Lefroy convened a series of meetings on an all-India basis, to bring together all the entomologists of the country. From 1915, five such meetings were held at the Imperial Agricultural Research Institute, and these formed the foundation of entomological knowledge in India. He was succeeded in the position of Imperial Entomologist by T. Bainbrigge Fletcher. He published Indian Insect Life, a summary of the major insects of economic importance in 1906, in association with Frank Milburn Howlett.
In the early 1920s, Lefroy was asked by Sir Frank Baines, Principal Architect of the Office of Works, to study ways of exterminating death watch beetles that had been found in Westminster Hall, beside England's Houses of Parliament. As a result, he went on to devise various successful formulations for pest control, and in time Lefroy began receiving regular orders from people who had heard about his work. In 1924, Lefroy and his assistant Miss Elizabeth Eades started supplying bottles of woodworm fluid from a small factory in Hatton Garden, which later led to the formation by them of a company called Rentokil Limited (now Rentokil Initial) in 1925.
- Indian Insect Pests (1906)
- Maxwell-Lefroy, H. 1909. Indian Insect Life: a Manual of the Insects of the Plains (Tropical India) Thacker and Spink, Calcutta. xii + 786 pp.
- Maxwell-Lefroy, H. 1910. List of Names Used in India for Common Insects Indian Agricultural Research Institute, Pusa, India. iv + 47 + xii pp.
- Manual of Entomology 1923
- Food of Birds in India (1911) C. W. Mason and Maxwell-Lefroy
- "Maxwell-Lefroy, Harold (MKSL895H)". A Cambridge Alumni Database. University of Cambridge.
- John L. Capinera (2008). Encyclopedia of Entomology. Springer Science+Business Media. ISBN 1-4020-6242-7.
Harold Lefroy was born on January 20, 1877, ... King's College, Cambridge ...
- Western Daily Press. 15 October 1925. p. 12 http://www.britishnewspaperarchive.co.uk/viewer/bl/0000264/19251015/128/0012 – via British Newspaper Archive. Missing or empty