George Thomson (1848-1933) was born in Calcutta, grew up in Scotland and emigrated to New Zealand at 20. He settled there, working as a teacher and analytical chemist, and was eventually elected to the House of Representatives in 1908. Thomson had an interest in natural history, but he was especially fascinated by the biological battles between native species of plants and animals and more recent arrivals. Realising New Zealand's unique advantage in having written records about the introduction of new species from the period of Captain Cook's second voyage in 1773 onwards, Thomson was able to trace the origins and spread of many plants and animals. This study, published in 1922, notes their locations and dates, and includes lists of foreign species officially designated as pests. It is a comprehensive guide to the non-native flora and fauna of New Zealand, providing valuable information about the country's ecological history.