WHOLE VOL. APPLIED ENTOMOLOGY HOWARD 279 



cently (1927). Boas is probably best known for his studies in the 

 comparative morphology and phylogeny of vertebrates and Crusta- 

 cea, but he made many remarkable investigations in applied zoology. 

 His studies of the cockchafers which were enormously destructive 

 on farm lands, in gardens, and in nurseries, led to the passage of a 

 bill requiring the collection of the adult beetles, that became a law in 

 1887. In 1887, 7,500,000 Danish pounds of the insects were collected, 

 and the number was steadily reduced year after year until in 1903 

 only 8,000 pounds were collected. He did not, however, attribute 

 this enormous decrease in number entirely to the destruction of the 

 adults. After a number of important papers on forest insects, he 

 published his " Danish Forest Zoology " in 1896 which is doubtless 

 one of the best textbooks of the kind in existence. It is admirably 

 illustrated and full of the personal observations of the author. It is 

 notable for its sharp criticism of many unfounded opinions and 

 worthless measures. 



In addition to his work in forest entomology, Boas lectured before 

 the veterinary students on the parasitology of domestic animals, and 

 he is said to have been largely responsible for the adoption of a sys- 

 tem for the rational control of the warble-fly by the compulsory 

 extraction of the larvae from the backs of cattle all over the country. 

 A government act was promulgated in 1923 establishing this process. 

 It is said that the operation of this act means at least 5,000,000 kroner 

 saved to Denmark each year. 



Pioneer work in agricultural entomology was done by the botanist, 

 Emil Rostrup, who, while Professor of Phytopathology at the Vet- 

 erinary and Agricultural College, published each year from 1885 to 

 1905 a survey of diseases and insect pests on farm crops. In the 

 1890's his daughter-in-law, Mrs. Sofie Rostrup, took up the study of 

 agricultural entomology and in 1907 was made Zoologist to the coop- 

 erative Danish agricultural associations. In 191 3 an Institute of 

 Phytopathology was founded under the leadership of K. Ravn, the 

 successor of E. Rostrup, and Mrs. Rostrup was appointed Zoologist. 

 But it was not until 1921 that this Institute was provided with suit- 

 able laboratories. Mrs. Rostrup remained Chief Zoologist until 1927. 

 During this period she wrote many papers on insects and nematodes, 

 and in 1920 published a book entitled " Noxious Animals of Our 

 Agriculture." The fourth edition of this book appeared in 1928, this 

 last edition being done cooperatively by Mrs. Rostrup and Dr. 

 Mathias Thomsen who succeeded Boas as Professor at the Veteri- 

 nary and Agricultural College. Mrs. Rostrup' s work has been very 

 sound, and more than that, it has been broad. In addition to her 



