DIVISION OF ENTOMOLOGY. 199 



Another veiy important line of worlc is the maintenance of records 

 of the feeding and otlier habits of injurious insects received from cor- 

 respondents, field agents, and others, and which are sent in for iden- 

 tification and for information in regard to the best means of control. 

 It is frequently found necessary, that we may judge of their status as 

 pests and be better able to indicate the most vulnerable point of 

 attack, to rear these insects, and, where possible, to ascertain their 

 full life histories from egg to adult. During the fiscal year 22(j species 

 not hitherto studied at this Department were given more or less study, 

 and the catalogue number of our biological series thus studied now 

 reaches 9,G67, this number being ihe accumulation from 1881 to date. 



A prominent feature of this work is the preparation of material 

 obtained from various sources for purposes of exhibition, for perma- 

 nent storage in the United States National Museum, for exchange 

 with other institutions in this and other countries, and for illustra- 

 tion and description. When insects that have not hitherto been 

 studied or are imperfectly known are obtained in their different stages, 

 illustrations are jirepared for use in the preparation of articles on 

 them. 



EXPERIMENTAL WORK WITH INSECTICIDES. 



During the year a considerable number of experiments with insec- 

 ticides and other methods of controlling insect depredations have 

 been conducted. A great many insecticide substances are constantly 

 being exploited in advertising columns of journals and papers, and 

 many of these come to this office for experimental examination and 

 test either from purchasers or the manufacturers. Most of these are 

 of very little value, or are combinations of old and well-known insec- 

 ticide substances, sold, however, as a rule, under their new form at 

 quadruple or many times their real value. The cooperation of the 

 Chemist of the Department has been often asked to determine the 

 composition of these substances. The necessity of work of this sort 

 having been frequently brought to his notice, the Chemist has estab- 

 lished a special section for insecticide analysis and investigation in 

 cooperation with the Division of Entomology, and during the year a 

 large series of examinations of common insecticide substances has 

 been nuide from materials collected, for the most part in open market. 

 "We have been assisted in the purchase of material by the entomolo- 

 gists of various experiment stations and by private individuals, the 

 effort having been made to get the insecticide materials over a wide 

 range of country, so that the analj^sis would represent material under 

 the identical conditions in which it would be purchased bj^ the farmer 

 or fruit grower. 



To determine the feasibility of eradicating household insects by 

 fumigation with hydrocyanic-acid gas, several valuable experimental 

 operations have been conducted with the result of the establishment 

 of the complete practicability of disinfecting houses by this means. 

 The latter has already been given considerable publicity in the daily 

 press, and the methods are fully detailed in Circular No. -40 (second 

 series) of this office. It has been demonstrated that this poisonous 

 gas can be used without risk to human life if the operation is carried 

 on with proper precautions, but no one is advised to undertake it 

 without having fully acquainted himself with the steps in the process 

 as indicated in the publication cited. 



