650 EXPERIMENT STATION EECORD. 



Para-dichlorobenzene as an insect fumigant, A. B. Duckett (U. 8. Dept. 

 Agr. Bui. 167 {liur,}, pp. 7, pis. 2). — Pani-tliclilorobenzene is a colorless, crys- 

 talline substance that volatilizes very readily as a colorless vapor with a 

 lieculiar ether-like odor, aud which has been known for many years but only 

 recently used as an insecticide. The vaiK>r is harmless to man and domestic 

 animals under ordinary conditions, but in many instances it is a specific poison 

 for insects. The greatest advantages which it possesses ai'e absolute uoninflam- 

 mabillty and its comparatively low cost, and the disappearance of the ether- 

 like smell upon exposui'e of the fumigated substances to the open air. It is 

 stated that it can be us«l in closed or occasionally opened cupboards and even 

 in sitting rooms without causing any inconvenience whatsoever. Fumigation 

 exi>erinients with stored product insects conducted during the spring of VJ14. 

 here reported in tabular form, show it to have destroyed all of ten species of 

 beetles exposed when used at the rate of 2 lbs. to 100 cu. ft. of .space at a warm 

 temi>erature but only 70 per cent were killed when exposed at a low tem- 

 perature. Flies and aphidids were destroyed when it was used at the rate of 

 S oz. to 100 cu. ft. of space. 



The author concludes from the observations and experiments that ]iara- 

 dichlorobenzene is an excellent fumigant against stored product insects, case- 

 bearing clothes moths, roaches aud ants, museum pests, and miscellaneous 

 house insects. It is also an effective substitute for potasium cyauid in collecting 

 bottles. 



An account of the chemical and physical properties of this chemical, pre- 

 pared by the Insecticide aud Fungicide Laboratory, is appended. 



A method of fumig'ating' seed, E. R. Sasscer and L. A. Hawkins ( U. S. 

 Dept. Agr. Bui. 186 (1915), pp. 6, figs. 2).— The need of a reliable method for 

 destroying insects present in seeds imported into this country, without injury 

 to the seed, led the authors to conduct experiments with a vacuum chamber 

 into which some gaseous insecticide could be introduced. The construction of 

 the apparatus devised, which consists of a fumigation chamber of iron tubing 

 36 in. long by 12 in. in diameter and an air pump, is described. The air pump, 

 driven by a motor aud capable of reducing the air pressure to the equivalent 

 of about 0.05 nun. of mercury, is used to secure an almost complete vacuum 

 of the fumigation chamber, which is fitted with a vacuum gauge, etc. 



The results of the experiment in M'hich hydrocyanic acid gas was intro- 

 duced into an air-tight chamber from which the air had been practically ex- 

 hausted, here presented in tabular form, show the method to be effective 

 for various seeds, insects, and conditions. In an experiment with ten avocado 

 seeds infested with larvne of Conotrachelus sp. and the broad nosed grain 

 weevil in all stages, an exposure of gas genei'ated from 4 gm. of sodium cyanid 

 for one-fourth hour was effective, fifty insects of different stages having been 

 killed aud all the seeds having germinated. Two gm. of sodium cyanid were 

 effective when the exposure was increased to one-half hour. 



It is stated that further experiments with special reference to the use of 

 carbon bisulphid will be conducted. 



Report of the entomologist, R. H. Pettit {Michigan St a. Rpt. 1914. PP- 232, 

 233). — A brief statement of the work of the year including the occurrence of 

 several insect pests of considerable economic importance. 



The carrot rust fly (Psihi ros(r) appears to have become established at Sault 

 Sainte Marie where it injured a small area of table carrots in 1913. It is 

 pointed out that in addition to carrots it attacks celery, parsnips, and perhaps 

 other vegetables, and that in Europe it has proved to be a difficult pest to con- 

 trol. The clover snout beetle {Sitoncs hispidulus) is reported to have been 



