384 The University Science Bulletin. 



it was evident that the temperature rise in the collar lagged behind 

 that of the chamber. This lag increased as the temperature rose 

 until at 122° F 'f here was a difference of nearly two hours. Thus 

 the steam was turned into the radiators at 8 a. m. and while the 

 chamber temperature reached 122° F. at about 4 p. m. the collar 

 temperature did not reach this until 6 p. m. 



COLD. 



A temperature control machine such as is used by this depart- 

 ment was used to demonstrate the possibilities of a freezing tem- 

 perature as a factor in the means of exterminating the pest. A 

 number of the specimens were placed in a vial in the temperature 

 machine. The temperature was reduced to two degrees below zero 

 and held constant for ten hours. The larvae were apparently dead, 

 but after a short period of incubation the specimens began to be 

 active again. I did not continue the experiments, as I realized the 

 impracticability of this means of extermination. 



CARBON DISULPHIDE. 



Carbon disulphide is a foul-smelling liquid that volatilizes readily 

 at ordinary temperature, and produces a heavy vapor that is 

 deadly to insects of all kinds when they are confined in a closed 

 space and must breathe it. In reading the data of the various books 

 and bulletins at hand on fumigation, it was found that this gas 

 is especially useful against species infesting stored grains and mills, 

 etc., overrun with Dermestidse, moth, and so on. There was reason 

 to believe, then, that the insects within the collars could be ex- 

 terminated if the carbon disulphide could be properly administered 

 to the interior of the collar. 



I made a carbon disulphide extermination test of the Trogoderma 

 inclusa as they occurred in the horse collars. I prepared a box 

 for inclosing one of the collars by covering it with paper on the 

 inside, and closing it with a tight cover. A small amount of carbon 

 disulphide was injected into the collar by means of a specially 

 devised syringe. The syringe used is modeled after the ordinary 

 type with the exception that a nozzle about four inches in length 

 was devised to reach all parts of the interior of the collar. The in- 

 strument is made of steel for durability and strength, as consider- 

 able force is required in making the insertion. The nozzle of the 

 syringe was inserted in the collar stuffing, entrance being made be- 

 tween the seams; thus there was no injury to the collar. It was 

 injected at spaces of about four or five inches apart. From six to 



