Ladislau (or Laszlo) Menyharth joined the Society of Jesus (Jesuits) in 1866. He taught natural history in the Jesuit college at Kalocsa, Hungary, where he also preached and served as rector of the college from 1885 to 1889. His main scientific interest appears to have been in botany and in 1877 he published (in Hungarian) on the plants of Kalocsa, Hungary. After hoping for an appointment in Africa for twenty years he was sent to Mozambique as a missionary in 1889. While stationed on the Zambezi River at the Baroma Mission outside Tete from 1890 to 1894 he collected plants in the vicinity. He was then transferred further up the river to Zumbo, on the northern bank of the river just east of where the borders of Mozambique, Zambia and Zimbabwe meet. Here he died of fever in 1897.
Menyharth made extensive collections of both flowering plants and cryptogams. Five of the fungi he collected were listed by P. Hennings in 1906, including a rust that was named Aecicdium menyharthi after the collector. He appears to have been more interested in lichens, as 55 species and varieties collected by him were listed by the Finnish botanist Edvard A. Wainio. In 1905 Dr Hans Schinz* published a comprehensive article in German on Menyharth's plants as a contribution to the flora of the lower Zambesi. Years later, in 1936, a series of four further papers on Menyharth's work, in Portuguese, appeared under the general title "Plantas Menyharthianas" in the Boletin da Sociedade Estud. Mozambique. The first, by A. de F. Gomes e Souza*, was mainly a biographical sketch of Menyharth. The fourth, by the same author, consisted of a list, with localities, of Menyharth's plants, compiled from various authors. The second was written by Schinz along the same lines as his earlier paper. The third, by the meteorologist Julius Fényi, dealt with the climate of Baroma. Menyharth's diary of his travels along the Zambezi was published in Maputo in 1938.
During his stay in Mozambique Menyharth made regular meteorological observations, recording atmospheric pressure, temperature, humidity, cloudiness, rainfall, and the direction and strength of surface winds. His observations were summarised in three papers in the Meteorologische Zeitschrift by Fényi, in 1896 and 1906 (for Baroma) and in 1904 (for Zumbo). The observations were also published in Meteorologische beobachtungen angestellt von P. Ladislaus Menyhárth, S.J., zu Baroma und Zumbo in Suedafrika in den jahren 1891-1897 (Kalocsa, 1895-1905). The observations for 1893 to 1897 were edited by Fényi and re-issued under a similar title in 1904 as a publication of the Haynald Observatory of the Jesuit college at Kalocsa.