OF WASHINGTON, VOLUME XIII, 1911. 197 



In 1882 his health failed, perhaps from an attack of tuber- 

 culosis, and his parents took him to Anaheim, California, 

 where he rapidly regained his health, and continued the col- 

 lection and study of insects. He began to specialize in Dip- 

 tera, especially the family Bombyliidae, which were very 

 abundant in Southern California. He sent many insects to 

 eastern entomologists, particularly to Provancher and to Le- 

 Conte and Horn. In 1893 Dr. Horn visited Mr. Coquillett 

 and found, among other interesting material, that Coquillett 

 had the sexes of a species of Calospasta, a discovery that 

 overturned the previous classification of the Meloidse. Mr. 

 Coquillett had at that time a very good knowledge of Cali- 

 fornian Coleoptera. He was also interested in the scale in- 

 sects and published in a local journal an article on the species 

 occurring in Southern California. 



In 1885 Coquillett was appointed a field agent of the Divi- 

 sion of Entomology of the United States Department of Agri- 

 culture, and (except for a brief period in 1886) was continu- 

 ously connected with it till his death. It was during this 

 short absence from the Department in 1886 that he began ex- 

 perimenting with hydrocyanic-acid gas as a remedy for scale 

 insects, and perfected the methods of its use. These methods, 

 improved in later years, are still the most reliable for destroy- 

 ing scale insects on citrus trees, and have been of enormous 

 value to the orange growers of California. In 1887 he re- 

 ceived from Mr. Albert Koebele the first shipments of ^^edalia 

 or Xoviiis cardi)ialis and had charge of rearing them. So 

 successful was he in this that in a few months there was an 

 abundance of this ladybird for distribution, and the orange 

 groves were soon free of the dreaded Icerya. Mr. Coquillett's 

 share in this, the most notable introduction of an insect enemy 

 in the history of entomology, can scarcely be considered less 

 important than that of Mr. Koebele. 



During his California residence Mr. Coquillett published re- 

 visions of various genera in the Bombyliidae and Asilidae, and 

 became well known as a dipterist. 



In 1893 the system of field agents was abolished, and Mr. 

 Coquillett came to Washington. He was employed in general 

 economic work, being the first to study the San Jose scale in 

 the East. Soon, however, he was detailed to study and 

 identify Diptera, and in 1896 was appointed Custodian of Dip- 

 tera in the United States National Museum, which position he 

 held at his death. 



His first important work on Diptera at Washington was on 

 the Tachinidse, perhaps the most difficult family in the order. 



