216 JOURNAL OF ECOXOMIC ENTOMOLOGY [Vol. 2 



leguminous seeds. At the present time comparatively little is being 

 done to prevent this enormous loss. If we consider also the damage 

 to such products in retail establishments, to household goods, tobacco 

 products, etc., and consider also that the total crop valuation for 1908 

 is approximately eight billion dollars as compared with five billions 

 for 1904, it would appear that the total insect damage for wliich 

 treatment might be made by fumigation will in the three classes of 

 nursery stock, green house crops and storage products probably 

 amount to between 200 and 300 millions of dollars annually. 



In spite of the enormous economic importance of these fumigauts 

 in insecticidal work, we must admit frankly that our use of them is 

 very largely based upon guess work, which only too frequently re- 

 sults in (1) lack of insecticidal efficiency, (2) more or less injury to 

 the plants or materials treated, (3) to unnecessary expense involved 

 in the waste of materials and frequently also in the time given to the 

 treatment. In case the treatment given is too weak to kill the insects 

 for which it is applied, all of the materials and time must be consid- 

 ered as wasted, and similarly there is a waste in the use of a large 

 excess above what is actually needed to kill the pests. 



Even with hydrocyanic acid gas, which has been used experi- 

 mentally much more than has Carbon di-sulfid, it is evident that there 

 is a great variation in the dosage advised by different entomologists 

 for the same purpose. No reasons for such variations are given, and 

 only too frequently the results obtained are such as to discredit the 

 reliability of entomological recommendations. 



Particularly in regard to the use of Carbon di-sulfid it is noticeable 

 that the great majority of recommendations are mere repetitions of 

 what some other man has previously advised. So far as we have been 

 able to learn, very few definite investigational experiments have been 

 attempted Avitli this fumigant, and unquestionably the recommenda- 

 tion which is generally given cannot be relied upon to accomplish the 

 desired result. 



It seems therefore that the field open to investigation is exceedingly 

 broad and sufficiently important to command the most careful investi- 

 gation possible. 



Scope of Work Contemplated. — In a general way we propose to 

 cover a fair range of subjects in the field outlined above. To learn 

 for each fumigant under different working conditions the general lim- 

 its of minimum dosage necessary to effect the destruction of various 

 insect pests, the maximum treatment endurable by various living 

 plants, both in green houses and out of doors ; and for nursery stock, 

 to determine the modifying influences of such obvious factors as light, 



