BU bm biN:, OF THE 
i. } USDEDARTMENT OF AGRICULTURE % 
No. 167 
Contribution from the Bureau of Entomology, L. O. Howard, Chief. 
February 10, 1915. 
(PROFESSIONAL PAPER.) 
PARA-DICHLOROBENZENE AS AN INSECT 
FUMIGANT. 
By A,-B.-DUCKETT, 
Scientific Assistant, Truck Crop and Stored Product Insect Investigations. 
INTRODUCTION. 
The purpose of the following pages is to determine the insecticidal 
value of para-dichlorobenzene as a fumigant, as well as to ascertain 
the injury, if any, to cloth fabrics and the effects of the vapors on 
plant life as well as upon the germination of seeds. 
Para-dichlorobenzene is a definite chemical compound, known for 
many years, but only recently used as an insecticide. It is a color- 
less, crystalline substance which volatilizes very readily as a colorless 
vapor with a peculiar ether-like odor. The vapor is harmless to 
human beings and domestic animals under ordinary conditions, but 
in many instances it is a specific poison for insects. It has an addi- 
tional advantage over the many other fumigants in that the odor 
does not cling to fabrics, etc., the characteristic ether-like smell 
rapidly disappearing upon exposure of the fumigated substances 
to the open air. Probably the greatest advantages that para- 
dichlorobenzene possesses over other fumigants are its absolute 
noninflammability and its comparatively low cost of purchase and 
application in proportion to the result obtained. 
EFFECTS OF INHALATION OF THE VAPOR. 
As stated, para-dichlorobenzene possesses only a weak ether-like 
smell, which, owing to the volatile nature of the substance, will pass 
off in a few hours if exposed to the air. Dr. Curschman, at the 
Greppin Works in Germany, concludes from a series of experiments 
that para-dichlorobenzene, when used as an exterminator for moths, 
etc., is virtually harmless to human beings, perhaps even superior 
to naphthalene in this respect. He goes further by stating that 
poisoning by para-dichlorobenzene to human beings through contact 
with the skin is impossible and that inhalation of the vapors of this 
product is perfectly harmless. According to him, para-dichloro- 
71117°—Bull. 167—15 
