Beyer: Trogoderma inclusa. 385 



eight drams were injected into each collar. The collar was then 

 inclosed in the box and left for twenty-four hours. After making 

 a thorough dissection of the collar, the various larval stages found 

 were all dead, and upon incubation no evidence of recovery was 

 noted in any of the larva? or adults. 



HYDROCYANIC-ACID GAS. 



Hydrocyanic-acid gas is a vapor very destructive to all life. The 

 gas is produced by adding potassium cyanide to sulphuric acid. I 

 used these in the following proportions: 



Potassium cyanide, 98 per cent pure 1 oz. 



Sulphuric acid, specific gravity 1.83 2 oz. 



Water 4 oz. 



I placed several of the infested collars in a closed chemistry hood. 

 I put an earthen vessel inside, containing water, poured the sul- 

 phuric acid slowly in the water, and then added the potassium cya- 

 nide, and immediately closed the hood and left the collars exposed 

 to the hydrocyanic acid for two hours, and then opened the hood 

 and let the gas escape. I then took the collars from under th-e 

 hood and examined the stuffing. There was no trace of life or re- 

 covery of the insects in the different stages. 



SUMMARY AND CONCLUSION. 



The Trogoderma inclitsa discussed in this paper were found in 

 horse collars that were sent to this department, requesting our ad- 

 vice and assistance in determining the kind and source of infesta- 

 tion and measures to be used in the control of this damaging insect. 



With regard to the source of infestation: Upon opening the col- 

 lars and finding grain in the straw stuffing, and upon examination 

 of the grain in many instances, I noted that it had been eaten upon 

 by the larvae of this insect, and through the instrumentality of my 

 series of investigations in relation to the life history, I found that 

 they thrived much better upon the grain than any other material 

 found in the make-up of the collars. This gave me a clue as to the 

 source of infestation. After getting some of the stored unthreshed 

 rye, and some of the rye seed which had been stored where it had 

 been raised, I found that a series of incubations produced exactly 

 the same species that was found in the collars. 



In considering the matter of infestation and the measures to be 

 used for its control, I suggest that the grain be eliminated as nearly 

 as possible from the straw to be used in the stuffing of the collars, 

 and there will be no liability of serious infestation. However, as I 



