18 N. H. AGR. EXPERIMENT STATION. [Bulletin 198 



in any number from unsprayed trees. The spray schedule includes both 

 single and double applications. 



Insect Record. — Under this project, which has been running continuously for 

 several years, there is opportunity to follow out two lines of study: 



The first of these includes a complete cross-index record of injurious insects 

 reported within New Hampshire. These records, which have now been main- 

 tained for several years, show the geographical location of the various species, 

 the relative abimdance and the food plants. Where records of this nature are 

 maintained for a considerable period of years and are compared with other 

 available records as to meteorological conditions and similar data, information 

 of general interest and of scientific value is disclosed. 



The second opportunity afforded is that of detailed study of a species that 

 unexpectedly exhibits unusual abundance. Under this phase of the project 

 an investigation was begun in 1919 in the control of termites which were found 

 to be seriously infesting a New Hampshire hospital. This investigation is 

 described below. 



Control of Termites. — Earlj' in the spring of 1919 a report reached the depart- 

 ment that termites, or so-called white ants, had been found in destructive 

 numbers in the basement of a New Hampshire hospital. Arrangements were 

 made to investigate the situation and to attempt measures of control. 



The termites were first discovered beneath a doorsill in the first floor of the 

 main or administration building of the hospital. On removal of a partition in 

 the basement, just beneath, it was found that the studding was honey-combed. 

 Several of the main beams supporting the building were then found thoroughly 

 infested, and it was discovered that the termites were at work in remote parts 

 of the building and had already caused extensive and exceedingly serious dam- 

 age. An investigation of the area surrounding the buildings was begun and 

 other colonies, or other parts of the same colony, were discovered. 



Timbers and partitions were removed. Experiments were undertaken to 

 determine the possibility of eradicating the insects within beams, partitions 

 and flooring by means of treatment with heat. The degree and duration of 

 high temperature necessary was found to be practical. Arrangements were 

 made to install temporarj' radiation. The entire basement of the main build- 

 ing was then treated with heat, and check observations maintained through- 

 out the treatment disclosed that it was successful. 



Further studies were undertaken to discover efficient barriers to prevent 

 further increase of termites into the buildings. These studies are still under 

 way. At the close of the work the data secured will be prepared for publica- 

 tion. 



Insecticidal Properties of Hellebore. — Supplementary to a part of the investi- 

 gation of the control of root maggots by insecticides, it was found feasible to 

 undertake a study of some properties of powdered hellebore. Although this 

 material has been in use as an insecticide for many years, its actual properties 

 have not been accurately determined. The investigation included the follow- 

 ing lines of inquiry: the availability of dried diluents of the powdered hellebore; 

 effect of dry heat on the insecticidal properties; value of aqueous extracts; 



