Oskar Theodor was an Israel

Israel

The State of Israel is a parliamentary republic located in the Middle East, along the eastern shore of the Mediterranean Sea...

i entomologist

Entomology

Entomology is the scientific study of insects, a branch of arthropodology...

 who specialised in Diptera

Fly

True flies are insects of the order Diptera . They possess a pair of wings on the mesothorax and a pair of halteres, derived from the hind wings, on the metathorax...

.

Born in Königsberg

Königsberg

Königsberg was the capital of East Prussia from the Late Middle Ages until 1945 as well as the northernmost and easternmost German city with 286,666 inhabitants . Due to the multicultural society in and around the city, there are several local names for it...

, Eastern Prussia (now Kaliningrad

Kaliningrad

Kaliningrad is a seaport and the administrative center of Kaliningrad Oblast, the Russian exclave between Poland and Lithuania on the Baltic Sea...

, Russia

Russia

Russia or , officially known as both Russia and the Russian Federation , is a country in northern Eurasia. It is a federal semi-presidential republic, comprising 83 federal subjects...

) he came to pre-Israel
Palestine

Palestine

Palestine is a conventional name, among others, used to describe the geographic region between the Mediterranean Sea and the Jordan River, and various adjoining lands....

 following a year's service as an orderly in the German

Germany

Germany , officially the Federal Republic of Germany , is a federal parliamentary republic in Europe. The country consists of 16 states while the capital and largest city is Berlin. Germany covers an area of 357,021 km2 and has a largely temperate seasonal climate...

 army in World War I

World War I

World War I , which was predominantly called the World War or the Great War from its occurrence until 1939, and the First World War or World War I thereafter, was a major war centred in Europe that began on 28 July 1914 and lasted until 11 November 1918...

. In 1921 he became an assistant in the Government of Palestine Department of Health, and in 1923 he transferred to the Malaria Research Unit in Haifa

Haifa

Haifa is the largest city in northern Israel, and the third-largest city in the country, with a population of over 268,000. Another 300,000 people live in towns directly adjacent to the city including the cities of the Krayot, as well as, Tirat Carmel, Daliyat al-Karmel and Nesher...

. In 1925 he became an assistant in the Department of Parasitology

Parasitology

Parasitology is the study of parasites, their hosts, and the relationship between them. As a biological discipline, the scope of parasitology is not determined by the organism or environment in question, but by their way of life...

 in the University of Jerusalem, where he remained for the rest of his career.

In 1928, Oskar Theodor returned briefly to Königsberg to complete his Ph.D. in entomology at the University of Königsberg.